Basketball Rules:
What is an Illegal Screen?

According to basic rules of basketball, an illegal screen is when an offensive player sets a moving pick on a defensive player.  This is usually done to help another offensive player have more room to slash to the basket or to catch the basketball.  An illegal screen is also known as a moving screen.  The personal foul counts towards the player's foul total as well as the team's foul total.  The defensive team gains possession of the ball when an illegal screen is called but in most cases they do not get to shoot free throws as a result of the illegal screen.

Learning all the offensive and defensive fouls will give you a better understanding of the basic rules of basketball, especially offensive basketball rules.