Football is the easiest to see as turn-based. One team plays offense, and then they switch to defense. Each play is a turn, called downs. A team gets 4 turns on offense, and if they haven't progressed far enough, the next team takes their turn on offense.

Baseball is even stranger. Not only do the teams take turns playing offense and defense, but each player himself takes a turn of their own. A pitch is a turn, and if the batter hasn't progressed before their hitpoints are depleted, the next batter takes his turn.

Basketball, on the other hand, is not turn-based. The world's most popular sport, Soccer, is even less turn-based than basketball. Soccer is interesting because it is almost completely fluid. The time keeps ticking no matter what, and it is a much looser game than any other popular sport. It's kind of like the jazz of sports.