What are the rules today?

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The rules of basketball are very easy to wrap your finger around. The team that has possession of the ball is the offense. The team that does not have the ball is the defense. The offense tries to get points, by getting the ball to go into the basket, without the defense stealing the ball. Whenever the offense gets the ball inside the basket, they get two or three points, depending on where they are on the court. After the offense makes a basket, the defense then gets the ball, and becomes offense. There is a spot on the court that is called the three-point arc. When a player shoots from behind this arc, they obviously get three points added to their score. Wherever a player shoots from inside the arc, they receive two points. The only time a player can get one point is when they are shooting a free throw.

What is a Violation?

There are many violations, but they do not count against your fouls.
Double dribbling is when you put two hands on the ball while dribbling.
A travel is when you stop dribbling and you take more than two steps. Double dribbling and traveling are the two most common violations known to basketball. 
Carrying is another violation; this is when you bring the ball too high. This is more common in the younger ages.
Jump ball is when two or maybe more players grab the ball at the same time. The ref will signal jump ball by two thumbs up, except when he/she does this it doesn't mean good job.
You may be asking yourself if there is a time limit for some things...or you may not be, but I am going to tell you them anyway. When en ta team takes the ball out on the opposite side of the court. They have ten seconds to get across, easy right? Not always. The other team may press, or put pressure on you to try to get the ball back.
When taking the ball out of bounds, the player throwing the ball in has five seconds to get the ball into play. If they do not, the other team gets the ball.

What is a foul?

There are many fouls that exist in the basketball world. There are offensive fouls and defensive fouls. Defensive fouls are the most common. There are also personal fouls, these are sometimes called technicals. When a technical is called, the player that was fouled gets to shoot two free throws. These free throws are different than regular free throws. The player that was fouled goes to the free throw line like normal, the other players have to be behind the half court line. Whether the shooter makes the basket or misses it, the same team that player shot the free throws gets the ball back.
Some personal fouls are intentional foul, illegal picking, pushing and holding. Setting a pick is when a player stands in the way of the defender, while the player with the ball goes around and either passes it, shoots it, or drives to the basket. An illegal pick is when you do not have your feet set in place when you are setting a pick. When you set a pick your feet have to be planted into the ground. You cannot move from that spot, you just have to stand there while the player goes around you. 
Two types of regular fouls that cause some fighting between the referees and the coaches are charging and blocking. These two are very hard to differentiate. The differences between these two are your feet and your hands. A charge is an offensive foul. It is when you basically run over the defensive player. The defensive player has to have his feet planted and hands straight up for this to be a charge. If his feet are not planted and his hands are not straight up, then it would be blocking. Blocking is a defensive foul. 

 

How many fouls do I get?

Each player that plays in a game of basketball gets five fouls per game. If you get five fouls, then you have to sit out the rest of the game. As a team, your fouls can come to hurt your team. If your team gets seven fouls in one half, then whenever you foul the other team they are in bonus. Bonus is also called one-in-one.  One-in-one is what you get when you are fouled and the other has seven, you get to shoot one free throw, if you make it you get to shoot another one. If you miss the first free throw, the ball is live and anyone can get it. If you make the first one, but miss the second then the ball is also live and anyone is able to pick it up. If your team has ten fouls, then the other team is in double bonus. Double bonus is when you get to shoot two free throws, whether you miss the first one or not.
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What do I get when I get fouled?

A free throw is awarded when a player gets fouled, they go to the free throw line which is just inside the three-point arc, and they can shoot as many as three shots. If a player gets fouled when they are shooting from inside the three-point arc and they make the shot, they get the two points for the basket they made and they also get to shoot a free throw. If the player is fouled while shooting from inside the arc, and misses it, then they get to shoot two free throws. If a player is fouled while shooting from outside the three-point arc and misses it, then they get to shoot three free throws. When a player is fouled while shooting from outside the three-point arc and they make it, they get two points for making the shot and they get to shoot two more free throws. After a free throw is made, the other team gets to take the ball out from right underneath the basketball hoop. If the free throw is missed, then the ball is live and whoever gets it gets to keep it. If you are fouled and you are not shooting, you get to take the ball out of bounds. As I explained in the paragraph above this, if the other team has more than seven team fouls, then you get to shoot one-in-one. If the other team has ten, then you are in double bonus.

What kind of positions are there? How many people play at a time?

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Five players can play on the court at the same time. There are also five different positions.
There is a center; this player is usually the tallest person on the team. They stay at the block, which is down by the baseline.
The forward is usually the next tallest player on the team. They are good shooters and can handle the ball well. 
Point guard is the one with the ball. They have the best ball handling skills on the team. They are usually smaller than the other players.
There are two guards. These are the players who have the best shot. They stay out on the wing, and wait to shoot, or drive.