The no-charge zone, the area under the ring where the defense cannot take a charge. It gives the offense more freedom in the paint and send them to the free throw line more.
In the 1997/98 season, the four foot radius “no-charge area” was first introduced. This was intended to promote freedom of movement and driving to the basket like the NBA in the past, before less offensive talented teams start winning games simply by working on their defense. And eventually evolving into all teams needed to play well defensively to win the NBA title, and taking a charge in the lane to prevent the highlight real dunk is an essential part of the game.
This rule originated to open up the lane, in the hopes of more (spectacular) dunks or encourage the players to go to the basket more often instead of settling for a jump shot. The NBA was doing this to generate more excitement in the game because they were losing they were losing fans during the regular season. This is due to a) the lack of excitement in the NBA because the season is too long, so each game do not count as much comparing to college basketball, b) improving technology, there are more affordable computer and video games and other sort of entertainments.