A slam dunk in basketball is an aggressive shot attempt where an offensive player with the ball leaps into the air and quite literally slams the ball into the net by grabbing the rim with one or two of his hands. A slam dunk counts as a field goal and earns a team two points. There a number of flashy ways to perform a slam dunk, but the minimum requirements for it to be called a slam dunk are that the ball is slammed through the hoop while touching the rim. Dunks can be done with a spin, backward, after an alley-oop, while hanging off of the rim, after passing the ball through one's legs; it can be as simple or as complex as a player desires.
It's said that the acclaimed sports broadcaster Chick Hearn coined the term slam dunk back in 1972, prior to that it was called a dunk shot. Slam dunks can be beneficial to a team in that it's almost certain that they'll go in; being so close to the rim makes them harder to block. You may even hear someone off of the court refer to something as a slam dunk when they think something is easy to do. Slam dunks can also boost team morale and send a message to the opponent that a team is ready to play aggressively. You'll often see slam dunks featured on sports networks' top 10 plays since they are such a highlight of the sport.
This is one of the most entertaining aspects of the sport and where being over six feet tall really comes in handy. Though it's easier for taller players to make a slam dunk, shorter players often use their jumping ability to reach the rim and slam the ball through the hoop. There are no limits to when and how players are allowed to slam dunk, as long as they don't commit an offensive foul by running through a set defender. It's most often done on fast breaks when players are one on one or even by themselves. During a regular offensive situation, slam dunks most often happen after an alley-oop pass, which is when a teammate throws the ball right near the rim for another player to quickly catch and slam dunk. In some situations, it can be seen as showing off, especially at lower levels of play, but in the NBA it's celebrated and done quite often.
It's celebrated so much that during the NBA's all-star break there is an entire event dedicated to slam dunking that debuted in 1984 and is still played annually to this day. In this competition, several players compete to get scored by judges based on the skill level of the slam dunk performed. Some of the best slam dunkers over the years include Michael Jordan, Vince Carter, Nate Robinson and Blake Griffin. Many credit Oklahoma State player Bob Kurland with being the first to dunk during an NCAA game back in the 1940s.