In variations like Texas Hold’em and Omaha, the turn is the fourth card placed on the community board. It’s also known as the 4th betting street.
For example, if a board in a community card poker variation reads Ks Qs Tc 8h 5d, the 8h card is the turn card. The first three cards are revealed on the flop, while the fifth card is called the river or 5th street.
