But the game is at it's best when it's played with all five athletes contributing on a consistent basis. So here we go.
But the idea starts with team defense.
There are, very basically, two types of team defense. They're called "Zone" and "Man-to-Man".
This is the type of defense primarily played in the NBA--though that may change (we'll cover that shortly). The idea, like the description says, is for each player on one team to be primarily responsible for player on the other team. Contrary to what you might think, that isn't determined by position. A Forward does not automatically cover one of the Forwards on the other team.
This is determined by the individual matchups as determined by scouting the other team. Let's use a hypothetical example. Larry Bird has to guard Magic Johnson of the Lakers. Magic is stong, and fast. but he likes to play with the ball--frankly, show off just a bit with his ball handling. Larry knows this because he's learned how Magic thinks by studying and playing against him. He can anticipate the move Magic might make that let's Larry steal the ball.
Now, Larry has stolen the hypothetical ball, but Magic knows Larry just as well, and anticipates that Larry will try to make a long pass down the length of the court (an "outlet pass") to a teammate for a quick basket. Magic tries to take it back. But since I'm a Celtics fan and this is my hypothetical example, Larry fakes Magic out, then passes out to Robert Parish. Parish makes the basket and the Celtics win the game.
is, that the Coach, after reading scouting reports, and seeing how his
own players have done in past games, decides who guards which players in
different situations. If you "cover your man" well enough, he is
less likely to be able to receive a pass--or if he does get the ball, you
might prevent him from taking an easy shot, or force him to pass the ball.
You might even be able to force him to turn the ball over--that is, to
commit an error, like going out of bounds, or traveling--that gives the
ball back to your team.
Here, you see an example of the Celtics on man-to-man defense. Dave Cowens (#18) is trying to reach the ball. Frankly, I can't tell which team took the shot. Look at the other Celtics players. Each one is watching both the ball--and his man. Each player on BOTH teams is trying to be in position to get the rebound if the shot misses, or at least prevent the man they're guarding to get the ball.
There's a drawback to the man-to-man defense, though. If the man you're guarding is faster than you, or you're not paying attention, he can zip right by you. That can be really embarrassing, especially if he keeps doing it. By that time, you're usually headed to the bench while someone else goes in to guard him. The same applies in reverse.