Commends allows players to send feedback for other players in-game, which is counted on each CS:GO profile. Think of it as a "like-button" for your in-game profile. You will get more respect from your team and it might as well boost your trust factor.

Join to the server and hold tab
Use your arrow keys to navigate to the player's name
Press enter and enter again on the "Commend" selection
Select one of the three choices to commend

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