The green square over an avatar means the player is currently online. Not sure about the red one though
Red or green squares?

What are they for? I can only say it doesnt matter if someone is online. Because i can watch this https://www.chess.com/game/143380207155
not that hard to figure out, red means they are playing, and green, online but not playing.
What are they for? I can only say it doesnt matter if someone is online. Because i can watch this https://www.chess.com/game/143380207155