When was the last time you tied a tie? For a lot of Web searchers in 2010, it had apparently been a while since prom.

Wearing a tie has become such a rare occasion that the concierge at the Mandarin Oriental Hotel in Washington, D.C., says the establishment offers a bow tie butler for fumbling guests. Just two years ago, a Gallup poll revealed that only 6 percent of American men wear ties. Blame the skill loss on the prevalence of business casual dress in the workplace and on the dwindling number of formal occasions, leaving more and more men clueless about neckties, ascots, and bow ties.

"A beginner should master the four-in-hand knot," says Aaron Britt, the men's fashion columnist on Pocket Square. This knot, which can be gently loosened for a casual look, carries the average gentleman through many occasions. Britt doesn't recommend wide knots such as the Windsor or double Windsor: "Wearing a very wide knot is rather like driving a Porsche -- flashy, masculine, and clearly overcompensating for some insecurity." The Windsor knot is sported by weather anchors and salesmen everywhere: Do they realize what the knot is saying?

For men who want flair but not flash, there is always the elegant bow tie. After all, Britt says, "No one ever murmured admiringly, 'Who's that guy in the necktie?'"

A bow tie is similar to the bow you tie with your shoelaces, and a nice, thick wool tie stands up well. Britt favors a navy cashmere bow tie with a yellow chalk stripe.

That sliver of fabric around a man's collar could express any attitude from breezy and rakish (a loosened four-in-hand knot) to daring and insouciant (the bow tie). If you're ready to up your sartorial game, watch "How to Tie a Tie" to get started.

--Eugenia Chien

Before joining Yahoo! as a Search editor, Eugenia Chien was a reporter at New America Media in San Francisco. Her work has appeared in the San Francisco Chronicle, on KQED, and on KALW. She crushes on geek heroes, transit enthusiasts, and animal lovers.

Asking a search engine for a foolproof weight-loss scheme? You might as well lump in questions like "How do I age backwards?" and "What's the meaning of life?" too.

Tough economic times aside, Americans live in a land of plenty -- or excess: supersized servings, heaping grams of sugar, and stress-induced cortisol to fatten bellies. Thus our perpetual search for the perfect plan: the diet plan, the meal plan, the exercise plan.

The scary seven-letter motivation, though, is "obesity," which is up 12% in searches compared to last year. More than 72 million of American adults (26.7%) are obese, and while it's not a word people like, it's the one heard on news broadcasts, talk shows, and government campaigns that aim to get our weights out of the danger zone. In the "tell us something we don't know" department, only one in six overweight Americans can lose weight and keep it off.

Not great odds, but how did the successful people do it? Apparently it helps to be female, single, diabetic, healthier overall, young, and college-educated. But single out one common factor, and it's that the weight loss was intentional. Not magical or improvisational but intentional.

That factor may explain why food diaries have become a favorite among dietitians. Not only does tracking calories give people a reality check, but they also have to commit to filling the diary out -- and that takes resolve.

What else motivates? People look for inspiring success stories. On TV "The Biggest Loser" and "Thintervention" have documented some emotionally intense weight-loss processes, and have propelled viewers to search for "biggest loser meal plans" and "biggest loser meal delivery." Celebrity before-and-after pictures had people scrambling to figure out "How did Kelly Osbourne lose weight?", "Kim Kardashian weight loss," and "Drew Carey diet plan." Even a former president, forced to slim down for a big wedding, got people hungering for the "Bill Clinton diet."

A slew of diets dominated searches: HCG (human chorionic gonadotropin) rocketed to the top in 2010, bypassing regulars like Atkins (pro-protein), South Beach (low-carb), cabbage soup (roughage-ing it), gluten-free, Mediterranean (the most balanced), Acai berry, Dr. Oz, and flat belly (based on a book). HCG was discovered in pregnant women's urine back in the 1920s, and in the 1950s a doctor discovered that boys being treated with HCG for delayed genital development also lost extra weight without hunger pangs. But HCG requires daily injections or creams, and the diet part is a tough 700 calories a day.

Research what works best for you, but know that the key to weight loss is a combination of exercise, diet, attitude, and lots of math. People go online every day looking for a handy "calorie calculator" and checking "How many calories should I eat?", "How many calories to lose weight?", "How many calories in a banana?", and "beer calories."

You may need a psychological boost. Many people search for quick solutions: "how to lose weight fast," "lose weight quick," "one-week diet," "how to lose weight in a week," and "how to burn fat fast." A University of Melbourne study claimed, "surprisingly, and against current beliefs," that a fast drop is better than a slow one -- at least when it comes to motivation, not for keeping the weight off.

--Vera H-C Chan and Eugenia Chien

Yahoo! Year in Review editorial lead for four years running, Vera H-C Chan dissects news events and search trends to share the why behind what's hot online and in the media. On Yahoo! her writing can be found all over, including in Buzz Log, TV, Movies, and her Shine blog Fast-Talking Dame.

Before joining Yahoo! as a Search editor, Eugenia Chien was a reporter at New America Media in San Francisco. Her work has appeared in the San Francisco Chronicle, on KQED, and on KALW. She crushes on geek heroes, transit enthusiasts, and animal lovers.

A pucker starts with 34 facial muscles, plus a few muscles in your head, neck, and shoulders as you tip your head forward. Your jawbone dips, lips touch, and your brain produces four different chemicals that can create a whirlwind of emotions. Heart rate races, oxygen enters, at least 26 calories evaporate. There, you've just kissed.

Kissing is an expression that most people have experienced since they were babies, but the intricacies of a romantic smooch still baffles the uninitiated. "Every kiss from infancy on reverberates with deeply felt echoes of attachment, pleasure, feeling good, and gives kissing its emotional power," writes Leonore Tiefer of the Kinsey Institute. "The lips and tongue have large representation in the brain -- every infant must suckle to survive. As we suckle, we feel, and we don't forget."

A kiss's meaning might sound intimidatingly primal. For some down-to-earth advice, Violet Blue, sex educator and the author of "Seal It With a Kiss: Tips, Tricks, and Techniques for Delivering the Knockout Kiss," has some tips. A kiss can be a barometer of chemistry, and Blue gets many questions from people who want to maximize their odds -- for instance, how to improve kissing, what's the best kissing trick, and the worst kissing mistakes.

For starters, practice is key. "If you don't have anyone to practice with, you can experiment with testing smooch sensations on the sensitive palm of your hand. But please wash it first," says a fastidious Blue. Once you've practiced on your own, it might be good to try with a willing participant. But how do you know if the person wants to kiss you?

If they're tight-lipped, forget it. A more welcoming sign, suggests Blue, is "if their lips are relaxed -- they mirror your body language." She suggests that you nibble on some mint leaves, sip delicious coffee or tea, or even scent your breath with the essence of chocolate. Avoid these faux pas: "smelly breath, scary noises, lots of drool, or face-chewing like a zombie." Noted.

So, to review: a sensitive palm for practice, plenty of fresh mint leaves, and enough facial muscles to pull together a pucker, and you too can find an answer to "how to kiss." Who to kiss, however, is another question altogether.

--Eugenia Chien

Before joining Yahoo! as a Search editor, Eugenia Chien was a reporter at New America Media in San Francisco. Her work has appeared in the San Francisco Chronicle, on KQED, and on KALW. She crushes on geek heroes, transit enthusiasts, and animal lovers.

If you're looking for work, welcome to the club. Nearly 15 million unemployed Americans vied for about 3 million open jobs in 2010, so the need to fine-tune resumes meant a lot of search queries.

Your resume needs to stand out, but forgo the scented stationery, glitter ink, and Gorilla Grams. What catches a recruiter's eye aren't bells and whistles but what you bring to the table. Says Charlotte Weeks, president of the National Resume Writers' Association, "Your resume is a marketing document that reveals why you are the perfect fit for a job, not a laundry list of everything you've ever done." So, unless you intend to teach everyone in accounting how to fetch and roll over, there's no need to include that dog-walking gig from the summer of '02.

Employers will eyeball the top third of your resume first: Devote that real estate to highlighting job-specific skills and outstanding accomplishments. If an industry heavyweight has praised your performance, consider putting a quote front and center. Most of your resume consists of you talking about how great you are: A few words from someone else, especially someone respected, make the point that others think you're great, too. Direct quotes are most effective; for example: "'The most talented salesperson I've ever hired' --Donald Trump."

The chronological vs. functional resume debate is one that only you can resolve. If you've held a string of impressive titles at name-brand companies and want similar work in the same industry, a list of your past jobs and responsibilities can be compelling. On the other hand, if you have little work experience, a spotty employment history, or are seeking another field, a document emphasizing the most transferable skills and abilities might be a better marketing tool. For the best of both styles, try the combination resume.

For those currently out of work, Susan Ireland, author of "The Complete Idiot's Guide to the Perfect Resume," recommends "filling in your employment gap with any paid or unpaid work that's relevant to your job objective." Volunteering, taking classes, or regularly defragging the computers at your nephew's school all count. "If you can't come up with anything relevant," advises Ireland, "fill your employment gap with a 'job title' that indicates your good character, such as family management, caregiver, travel, or something wholesome you were doing."

Applying online? Follow the instructions. Some employers don't open attachments, so if a job listing requests a resume in the body of an email, do it. If it's OK to send an attachment, put your name in the document's title so that HR can find it easily. And never send your resume into the world unaccompanied; always compose an enticing cover letter to introduce yourself and your skills.

Convert your resume to a text (or ASCII) file. Yes, all the bolding, italics, and underlining that look so awesome on paper will disappear. But in exchange your potential new boss will see exactly what you sent, not a series of wobbly hieroglyphs. For the tech-savvy, senior corporate recruiter Michelle Rowe advises using Microsoft Word resume templates instead of online resume builders, and saving in PDF format. PDF and Word files are easiest to send by email and through the applicant-tracking systems that big companies use.

Make sure your work history corresponds to your Web presence, such as your LinkedIn profile. Employers searching for you online -- and they will search -- should find nothing but solid credentials and glowing references.

Whether your resume is electronic or hard copy, details count: Make sure every line is proofread and office-appropriate. No matter how qualified you are, no one's going to believe that you are if your email address is unicornluvr88@emailservice.com. Create an address like firstname.lastname@emailservice.com that's easy to search and sort for, and as professional as your interview suit. That way, you'll soon have a reason to wear it.

--Mireille Majoor

Mireille Majoor writes, edits, and tweets for the Yahoo! Search Blog and edits the Yahoo! Spark blog. She has written and edited for such publishers as the Better Business Bureau, Hyperion, Penguin, and HarperCollins, on subjects ranging from Anastasia to zeppelins. Mireille is also the author of two books for children, one about the Hindenburg explosion and the other about the sinking of the Titanic, making her the undisputed master of disaster for the under-12 set.

Jessica Hilberman contributed to this article.

Sorry, Team Edward: The world's only immortal animal doesn't have pale marble skin, artfully disheveled bronze hair, or topaz eyes that pierce your soul. The world's sole immortal animal is downright unsexy.

Meet the Turritopsis dohrnii, a jellyfish that scientists in 2009 declared "the only immortal animal" in the world. The round, slightly opaque bulbous body of the jellyfish is accented with floppy, thin tentacles -- not exactly the image of a sexy beast.

How could this be? And how do you prove immortality anyhow? The Turritopsis dohrnii turns back time by reverting to its first stages of life in a process called transdifferentiation. Just as a salamander might regenerate its limbs, this jellyfish, native to the Caribbean, can regenerate its cells over and over again. Instead of dying, the Turritopsis dohrnii "transforms all of its existing cells into a younger state," says Maria Pia Miglietta, who led the study at the Smithsonian Tropical Marine Institute in Panama.

Miglietta, who is now a researcher at Pennsylvania State University, said that "studying Turritopsis and its life cycle can bring a great contribution to science." Her study drew a huge spike of interest not only among Web surfers but also from media, the scientific community, and students, she says.

The jellyfish is scientifically fascinating but doesn't quite measure up to the immortal beings in literature and film. Plus, Turritopsis dohrnii provokes a slew of compelling, philosophically tinged questions: Does self-regeneration really count as immortality? Or is this jellyfish really an example of the living undead?

As any respectable horror fan can tell you, there's a world of difference between undead and immortal. Steve Mockus, the author of "How to Speak Zombie" and editor of the forthcoming "Worst-Case Scenario Survival Handbook: Paranormal," can attest to this. "Both zombies and vampires are undead, but zombies aren't immortal, because they keep decaying," he explains. Besides, zombies don't get nourishment from chowing down on humans, as vampires do.

"Neither one is 'alive,' but one of them eventually expires," Mockus says. "So a zombie dog wouldn't be immortal. But a vampire dog, now you're talking." As for the possibility of immortal vampire jellyfish, well, luckily for us, jellyfish have no teeth.

--Eugenia Chien

Before joining Yahoo! as a Search editor, Eugenia Chien was a reporter at New America Media in San Francisco. Her work has appeared in the San Francisco Chronicle, on KQED, and on KALW. She crushes on geek heroes, transit enthusiasts, and animal lovers.

Paranoia about what comes from the tap runs long and deep. Ironically, much of the bottled water consumers buy to avoid tap water comes from the tap too. So, which city has the best tap water, and how do you find out if yours is good?

For New Yorkers, water quality is a point of pride, while San Franciscans claim that its Hetch Hetchy's water wins the purity test. They're not bad, but the best tap water of the U.S.'s big cities (more than 250,000 residents) flows from Arlington, Texas, according to Nneka Leiba, an analyst with the Environmental Working Group. The nonprofit's study, which aims to educate consumers about water pollutants, safety, and regulation, is a user-friendly field guide to consuming H20 in 48,000 communities across the United States.

Not a Lone Star? You can still take back the tap wherever you live. Good water depends on three criteria: a clean source (in the U.S., these are mostly from rivers and groundwater), utilities that test extensively for both regulated and unregulated contaminants, and infrastructure that safely transports water to consumers.

Otherwise some bad stuff could be lurking in your pipes, and you wouldn't even know what. Says Leiba, "It's hard to rank which contaminant is the worst, and some top contaminants of concern are not tested for," mostly due to differences of opinion between the government and utilities regarding water policy. There are unregulated chemicals that count as contaminants but that the EPA doesn't require utility companies to test for, according to EWG senior scientist Olga Naidenko.

Overall, the more problematic contaminants we know about include disinfection by-products (used to treat poor-quality source water), nitrates from unrestrained agricultural run-off, arsenic, pesticides and herbicides in heavy agricultural watersheds, and industrial chemicals from manufacturing and disposal sites.

Think your tap water tastes fine? It very well could be, but funny smells and tastes can be indicators of problems with what's in your water, such as other people's prescription meds and copepods, a tiny, shrimplike creature.

Now the good news: The fix is easy. A simple carbon filter could be a big help, though Leiba advocates a more advanced, reverse-osmosis filter if it's in your budget -- cost runs about $45 to $200. To plunge into the subject, check out the EWG filtration guide.

--Jessica Hilberman

Jessica Hilberman is a Yahoo! editor and a die-hard generalist. In her former freelance life, she edited and wrote for an eclectic assortment of publications, including Wired, Sunset, Self, Teen People, DailyCandy, America.gov, and even Poultry magazine.

Feel like the days are getting shorter? Well, they did. On February 27, 2010, the massive 8.8 earthquake centered in Maule, Chile, torqued the earth so hard that our planet's axis shifted -- though not so much that you'd notice. According to scientists at NASA's Jet Propulsion Laboratory, computer models show that the 2.76-inch shift shaved 1.26 millionths of a second off each day.

And it's not the first time an earthquake has shortened the day. Geophysicist Richard Gross, the Earth rotation-variation expert (say that three times fast) who calculated the change, also predicted that the 2004 Sumatra-Andaman earthquake, which measured a whopping 9.0 and caused a tsunami that took thousands of lives, shaved 6.8 millionths of a second off Earth's day.

So, could the day get trimmed again? Sure, but it takes a particular type of quake: Megathrust earthquakes, the most powerful kind known to science. Megathrust quakes occur at subduction zones, where one tectonic plate can be forced under another, creating huge earthquakes, often deforming the ocean floor and tweaking the rotation of our planet.

Megathrust quakes have been reported as far back as the year 365, when the African and Eurasian plates clashed, causing widespread destruction around Crete. The resulting tsunami in Alexandria was documented by Roman historian Ammianus Marcellinus, in the first account of an earthquake followed by a drastic recession of the sea and then a huge wave.

--Jessica Hilberman

Jessica Hilberman is a Yahoo! editor and a die-hard generalist. In her former freelance life, she edited and wrote for an eclectic assortment of publications, including Wired, Sunset, Self, Teen People, DailyCandy, America.gov, and even Poultry magazine.

How many ways to love in 2010? Count 'em up.

Drunk love: Vinny telling Snooki that she takes his breath away, even though she's orange. Fan love: people camping out overnight to get tickets to a Justin Bieber concert. Hopeful love: Larry King calling off his divorce from wife No. 7. Familial love: Heidi Montag threatening to get a restraining order against her mom.

No wonder people feel they have to turn to the Internet to ask, What is love?

Love definitely comes in cycles. In February, understandably, people searched for "how to tell someone you love them," what to write in a love letter," "how to fall in love," and "why does love hurt."

Scientists say that the origin of love has a name: oxytocin. The hormone plays an important role in pair bonding, orgasm, and maternal behaviors. Scanning the brains of couples who say that they're madly in love, Helen Fisher, a researcher at Rutgers University, found that some of the behavior patterns actually resemble obsessive-compulsive disorder. Oxytocin isn't just the culprit in romantic couplings: Mothers with high levels of oxytocin seem to bond better with their offspring, while moms suffering post-partum depression have low levels.

Most people are inclined to view love less as a disease, more as a passion that inspires poetry and connects soul mates. Pop culture tells us that love is looking across a crowded dance floor and reading your future in someone's face.

"The fact is, not all love comes as a thunderbolt," says Dr. Pepper Schwartz, author of "Prime: Adventures and Advice on Sex, Love, and the Sensual Years" and chief relationship expert for PerfectMatch.com. Even if two people don't feel an instant physical attraction, sometimes just a twinkle in the eye, the way someone moves, or the sound of a voice can create need and desire. "There are many kinds of love: selfish, insecure, anxious, warm, comfortable, passionate, and sacrificial," Schwartz says, "but they're all connected."

--Eugenia Chien

Before joining Yahoo! as a Search editor, Eugenia Chien was a reporter at New America Media in San Francisco. Her work has appeared in the San Francisco Chronicle, on KQED, and on KALW. She crushes on geek heroes, transit enthusiasts, and animal lovers.

More than three centuries after Benjamin Franklin's kite experiment, the cause of lightning is still a bit mysterious.

Scientists believe that static electricity is the root cause of lightning flashes.  In a storm, water and ice particles in a cloud collide, which causes a negative electric charge to form. To neutralize this imbalance, the extra electrons are transferred to something nearby that has a positive electric charge, such as another cloud, the ground, or a church steeple. The electrostatic transfer takes place in the spectacular flash that you see, and it can contain 100 million to 1 billion volts of electricity.

In the weeks after Eyjafjallajokull blew its top in April, jolts erupted out of the ash. Volcanic eruptions, as well as sandstorms and snowstorms, can create the same imbalances in electric charge that occur during thunderstorms.

Lightning comes in different forms, as the Palm Beach Daily News notes: "[c]loud-to-ground lightning, ground-to-cloud lightning, cloud-to-cloud lightning, bead lightning, ribbon lightning, staccato lightning, forked lightning, sheet lightning and heat lightning. ..."

One form, though, may be only in our minds: Ball lightning looks like a grapefruit-sized ball that hovers or rolls on the ground before it disappears. Austrian researchers think that incidences might be an illusion caused by a real lightning strike's magnetic field, which creates a phosphene image in our brain. (Think of those cartoons when a character sees stars after a conk on the head.)

We don't have everything figured out about lightning, but one thing is for sure: You don't want to get struck by it, as about 270 Americans were this year. The best policy in a thunderstorm is to head for shelter -- or, as the the slogan for this year's 10th anniversary Lightning Safety Awareness Campaign states, "When Thunder Roars, Go Indoors." The campaign, sponsored by NOAA and the National Weather Service, also recommends waiting at least 30 minutes after that last thunder clap before heading out again.

If you find yourself outside in a lightning storm, you should avoid elevated places; open areas; tall, isolated objects; and bodies of water. And your elementary school teacher probably told you this, but don't hide under a tree.

What's the lightning capital of the U.S.? Florida, especially in summer. As for the world, that honor belongs to Kifuka in the Democratic Republic of the Congo, where 160 bolts hit every year.

--Katherine Leahey

Katherine Leahey manages the help pages for Yahoo! Finance and Yahoo Groups. Before coming to Yahoo, she worked in marketing and public relations.

Eggs had finally left behind their bad reputation as artery cloggers, and then in 2010 they got caught up in the most massive food recall in years. Nearly 2,000 Americans got sick from eggs contaminated with salmonella, possibly from infected chicken feed in Iowa. But the recall didn't seem to stop people from eating eggs, judging from the number of searches on Yahoo! for how to cook eggs. The top question? How to boil an egg.

Boiling an egg only sounds simple. In Julia Child's "The Way to Cook," she prescribes covering the eggs with cold water, bringing them to a boil, turning off the heat, and letting the eggs sit for "exactly 17 minutes." Then you should chill the whole eggs in an ice bath and briefly shock them in boiling water again to separate the egg whites from the shell.

What makes Julia's method perfect? She says in her book that the way she boils eggs produces tender egg whites, and "there is not the faintest darkening of yolk where the white encircles it" -- overheating triggers a chemical reaction that darkens the yolks, she says.

Everyone prefers their eggs boiled differently, and it takes mere seconds for the egg to go from a soft, runny center to a hard, fully cooked yolk. In fact, because eggs are so temperature-sensitive, egg cookery is a "good barometer to judge the skill of a chef," says Jason Berthold, a former sous chef at the famed French Laundry and now executive chef at San Francisco's RN74. Berthold's restaurant goes through 360 dozen per week, used in dishes from poached eggs to pasta to ice cream.

If you want to go a step beyond a simply boiled egg, try his method. Berthold is the mastermind behind the French Laundry's coddled egg, which is cooked in a glass jar only a little larger than the egg itself, for exactly three and a half minutes, then served with black truffles and butter.

--Eugenia Chien

Before joining Yahoo! as a Search editor, Eugenia Chien was a reporter at New America Media in San Francisco. Her work has appeared in the San Francisco Chronicle, on KQED, and on KALW. She crushes on geek heroes, transit enthusiasts, and animal lovers.