1. Kissing is good for you. A few of its benefits: it can help reduce dermatitis and blemishes. It can also help fight tooth decay because the extra saliva it produces cleans out your mouth. Kissing for a minute can burn up to 26 calories. And practiced regularly, kissing may even add a few years to your life. One study claimed that men who kiss their wife every morning before leaving for work live five years longer.

2. On the other hand, kissing can spread germs. One peck can contain up to 80 million new bacteria, and frequent kissing can change your microbiome.

3. On average, we spend two weeks out of our lifetimes kissing. That’s 336 hours of lip service.

4. The longest movie kiss was a 3-minute and 23-second steamy liplock between actresses Necar Zadegan and Traci Dinwiddie in Elena Undone (2010).

5. The longest kiss in the real world belongs to Ekkachai and Laksana Tiranarat. In 2011, the young Thai couple locked lips continuously (without a break) for nearly two days straight—a record-setting 46 hours, 24 minutes and 9 seconds.

6. There are many arcane laws on the books about kissing. In Indiana it is illegal for men with mustaches "to habitually kiss human beings." Presumably, any other species is fair game. In Colorado’s Logan County, a man is forbidden to kiss a woman while she’s asleep. And in Hartford, Connecticut, men are apparently prohibited from kissing their wives on Sundays.

7. What about kissing the Blarney Stone? The legend goes that the builder of Blarney Castle, one Cormac Laidir MacCarthy, was involved in a lawsuit and appealed to the Irish goddess Clíodna for help. She told him to kiss the first rock he found on his way to court. The result was that he pleaded his case with great eloquence and won. MacCarthy then laid the lucky stone into the parapet of his castle.

8. Like snowflakes and fingerprints, no two lip impressions are the same.

9. We all know that x’s represent kisses in print. But why? Back in medieval times, before most people could read or write, they signed their name with an x, then kissed the mark to show their sincere intent.

10. The term "French Kiss" has been around since Victorian times, and first appeared in print in a WWI-era book called Private Lindner’s Letters: Censored and Uncensored. The thought was that the French were experts in passionate romance. In France, they call it baiser amoureux (love kiss) or baiser avec la langue (kiss with the tongue). The word galocher, the verb for to kiss with tongues, was added to French dictionaries in 2014.

11. The first interracial kiss on television was featured in a 1966 episode of Star Trek. Originally, the script called for Spock and Lt. Uhura to lock lips, but according to actress Nichelle Nichols: "Bill Shatner said, 'Oh no! If anyone is going to get to kiss Nichelle, it’s going to be me!' And so they rewrote it and we all laughed about it." Fan mail was overwhelmingly positive, and one particular fan stands out for Nichols. "[Dr. Martin Luther King told me] that I was one of the most important people in his family," Nichols said. "That they watched Star Trek and that I was a role model and their hero."

A version of this article ran in 2011.