It's website: www.chessclub.com
Other than playing chess, you can also watch chess videos and take chess lessons.
Other popular chess servers are:
- Chess.com: http://www.chess.com
- ChessKid.com: http://www.chesskid.com
- Free Internet Chess Server (FICS): http://www.freechess.org/
- Playchess.com: http://play.chessbase.com/js/apps/playchess/
http://www.completechesscourse.com/puzzles.html
http://onemovecheckmate.blogspot.com/