Why do tennis players wear a band around their wrists?

Answer 1

Quite often, it is simply a sweatband, i.e. a small piece of towel used to easily wipe sweat form the player's brow.

Some players also use wrist supports to reinforce their wrists.

Answer 2

Tennis players wear a band around their wrists to absorb sweat and improve their grip on the racket during play. This helps prevent the racket from slipping out of their hands and allows players to maintain control and precision in their shots.