The French Defense starts 1 e4 e6. It is played often with agressive play on the Queenside for Black and Kingside for White,each having castled on the opposite side, and can form into either an open or a closed game depending on whether the Advance variation or the Exchange variation is played.
e5 (refusing taking the pawn, which leads into the Exchange variation)
Black often plays 3...c5 here to threaten the centre and form a good foundation on which to start his attack, with moves like Nc6, Qb6 and Bd7. The light squared bishop and kingside pieces are hard to develop which is why this opening is not commonly played in grandmaster chess. For White, the b2 pawn has to be remembered as well as the f2 pawn (if an exchange in the centre takes place). Moves such as b3, c3 and Nf3 are common. Also, after taking the pawn on d4 and removing the Knight on f3 then the e5 pawn has to be remembered.
White prefers to open up the e file and play an altogether more open position. The position is roughly equal, leading to a drawn position. As White is generally said to have the advantage in the starting position the position is not favourable for White and so usually when playing the French Defense the some other variation is preferred.
A pretty wild variant where common opening principles are often neglected. Black adds pressure to e4 by pinning the defending knight. Most often these minor pieces will be exchanged and white's queenside will be weakened in return for space and quite some potential of attacking on the kingside.
White starts out with e4, controlling the center. Wanting to avoid a pawn exchange, black moves his king's pawn to e6. White gains more control of the center with d4. Black sees a weakness in this position and moves to d5, attacking white's undefended king pawn. White defends with Nc3, not only defending his pawn but also attacking black's queen pawn. After black's Nf6, white moves his bishop to g5 to pin the knight to the queen. Black defends with Be7, not only getting rid of the pin but also enabling castling. White moves his pawn up to attack the knight. Black retreats, attacking both the pawn and the bishop. White exchanges bishops, and the queen takes white's dark bishop. White develops his own queen, allowing him to castle. After black castles, white moves his f-pawn to defend his e-pawn. Black attacks the d-pawn with c5. Both players develop their knights to fight for control of the d4 pawn. White starts an exchange by taking the c5 pawn, and black uses his knight to take out white's pawn. White castles as black develops his rook's pawn. After developing a couple pieces, white moves his knight to attack the c6 knight. Black takes the knight, and white re-captures with his e2 knight. Black moves to the c-file, and the middlegame starts.