Rules for variants

Is there a place where the rules for the variants are explained?

King of hill: http://fr.lichess.org/king-of-the-hill
Chess960: en.m.wikipedia.org/wiki/Chess960
Antichess: http://en.m.wikipedia.org/wiki/Losing_chess
Atomic: http://www.freechess.org/Help/HelpFiles/atomic.html
Tree-check: http://en.m.wikipedia.org/wiki/Three-check_chess

Thank you a lot.