Why are rooks better than knights? Generally, rooks are considered to be much better than knights.  Why is that?  Is it a myth or are they really better?  Are there situations where a knights may be better that a rook?  I usually think that rooks enter the game a bit later and this reduces their value during the early stages of the game.
Rooks are more suitable for open games where there are open lines. Knight are better for more closed games. Knights have the benefit of jumping over other pieces and rooks have the ability to move quickly whereas knights move very slowly.

Also, remember that you can't checkmate with just a Knight and King, so Rooks are probably more powerful in the endgame especially when the board is wide open.