Premove

Premove, in internet chess, refers to the act of a player making a move before it is their turn to move. This option is available on chess websites such as the Internet Chess Club and the Free Internet Chess Server as well as Chess.com.
Description.
To use premove, a player makes a move in the same way they would move if it was their turn. After their opponent moves, the original player's move is immediately made, assuming that the move is still legal. Premove is not available in over-the-board chess.
Premoving is only recommended if a player is very low on time, as it entails the risk that the opponent will do something unexpected that leads to the premove no longer being an appropriate play. However, it can save a player a split second, making it useful for fast chess. It is also useful to save time when the opponent's reply is forced, meaning there is no possibility of a premove backfiring due to an unexpected move.
Blocking premove.
Many players consider the use of premove unfair. Thus the Internet Chess Club allows players to block users who use the premove option.