Since 2002, the third Thursday of April is recognized as National High Five Day—a 24-hour period for giving familiars and strangers alike as many high fives as humanly possible. A few University of Virginia students invented the day, which has since evolved into a “High 5-A-Thon” that raises money each year for for a good cause. (For 2019, it's CoachArt, a nonprofit organization that engages kids impacted by chronic illness in arts and athletics.) Here are a few more facts about the history of the hand gesture to get you in the high-fiving spirit.

UP HIGH

That may sound like a lot of celebration for a simple hand gesture, but the truth is, the act of reaching your arm up over your head and slapping the elevated palm and five fingers of another person has revolutionized the way Americans (and many all over world) cheer for everything from personal achievements to miraculous game-winning plays in the sports world. Psychological studies on touch and human contact have found that gestures like the high five enhance bonding among sports teammates, which in turn has a winning effect on the whole team. Put 'er there!

Down Low

There is some dispute about who actually invented the high five. Some claim the gesture was invented by Los Angeles Dodgers outfielder Glenn Burke when he spontaneously high-fived fellow outfielder Dusty Baker after a home run during a game in 1977. Others claim the 1978-79 Louisville basketball team started it on the court. Since no one could definitively pinpoint the exact origin, National High Five Day co-founder Conor Lastowka made up a story about Murray State basketballer Lamont Sleets inventing it in the late 1970s/early 1980s, inspired by his father's Vietnam unit, “The Fives.”

Regardless of which high-five origin story is more accurate, there is little question of its roots. The high five evolved from its sister-in-slappage, the low five. The gesture, also known as “slapping skin,” was made popular in the jazz age by the likes of Al Jolson, Cab Calloway and the Andrews Sisters.

Gimme Five

As the high five has evolved over the past few decades, variations have developed and become popular in and of themselves. Here are five popular styles:

The Baby Five

Before most babies learn to walk or talk, they learn to high five. Baby hands are much smaller than adult hands, so grownups have to either use one finger, scrunch their fingers together or flat-out palm it.

The Air Five

Also known as the "wi-five" in the more recent technology age, this one is achieved just like a regular high five, minus the hand-to-hand contact. Its great for germaphobes and long distance celebrations.

The Double High Five

Also known as a “high ten,” it is characterized by using both hands simultaneously to high five.

The Fist Bump

It's a trendy offshoot of the high five that made headlines thanks to a public display by the U.S. President and First Lady. Instead of palm slapping, it involves contact between the knuckles of two balled fists. In some cases, the fist bump can be “exploding,” by which the bump is followed by a fanning out of all involved fingers.

The Self High Five

If something awesome happens and there's no one else around, the self high five may be appropriate. It happens when one person raises one hand and brings the other hand up to meet it, high-five style. Pro-wrestler Diamond Dallas Page made the move famous in his appearances at WCW matches.

You're too slow!

Don't fall for that old joke. The key to a solid high five is threefold. Always watch for the elbow of your high-fiving mate to ensure accuracy; never leave a buddy hanging; and always have hand sanitizer on you. Have a Happy High Five Day!

This article has been updated for 2019.