When a team controls the football, they are on offense and have possession of the ball. If a player goes to pass to a teammate and the other team intercepts it, the other team has now gained possession.
Having possession of the ball is a powerful thing in football. Your team is on offense is trying to score by moving the ball towards the opposing team's end zone on the field. Once a team maintains possession, it can become harder and harder for the other team to gain possession. The team with the most points at the end of a football game is the winner, so it's essential to maintain possession of the ball or work to cost the other team a turnover so your team can gain possession again.
There are two ways that teams move the ball on the football field where they can maintain possession:
Throughout both of these ways, your team should work to keep possession of the ball on your team.
Football teams may change possession of the ball after halftime. It all depends on the coin toss and which team got the ball at the start of the first half. If a team chose to defer on the coin toss, they get their first choice of the coin toss options at the start of the second half. So although possession can reflect during the game of who performs better, sometimes there are technicalities, like the coin toss, that can affect possession, too.