The French defence is a chess opening, one of the asymmetric replies to 1.e4, namely 1...e6. It is the third most popular reply to 1.e4. Often, Black plays more actively on the queenside while White plays more actively on the kingside.
A problem that Black often has in the French defence is finding a way for his light squared bishop to become active. Although this is true, it may not matter if Black knows what he is doing. The defence has a reputation for reliability, and has been played by many great players (such as Botvinnik), and has featured in several world championship matches.
Typical examples go: