Modern Variation (4.Nf3)

The idea

After 4.Nf3, White supports e5 with a piece instead of more pawns. Black's main choices are 4...Bg4, pinning the knight, 4...g6, the Alburt Variation, and 4...dxe5, the Larsen Variation.

Plans for White

Develop with Be2, castle, and play c4 to gain more space when it's safe. White wants to keep e5 or exchange it so that d4 stays strong. h3 can put the question to a bishop on g4.

Plans for Black

Pin with ...Bg4, fianchetto with ...g6, or take on e5 and follow with ...c6. In each case Black's plan is to pressure d4 and e5 with pieces, keeping the position solid.

Watch out for

For Black, the bishop pair. After ...Bg4, Black often gives it up with ...Bxf3, which is fine only if White's center is weakened by it.

For White, d4. Once e5 is exchanged, d4 can come under pressure from ...Nc6, ...Bg4 and ...c5, so keep it protected.