The Fourth Round:  

 The fourth (and final) betting round starts again with the player left of the button, and bets and raises are limited to the upper limit of the stake structure ($10/$20 game, $20 would be the upper stake). When we say the bets are limited to $20, it refers to a single bet of the value of $20, so when a user places “BET” then it is $20, a “RAISE” would be $40 (includes one additional bet and a call on the previous bet placed by a player). Bets can be placed by playing any of the following options – Bet, Call and Raise.

 Combinations of these options are available to the player depending on the action taken by the previous player. The first player placing a bet (the player left to the Button) would get the Bet option.