Exchange Variation

The idea

After 5.exd6, Black must choose between the solid 5...exd6, leading to a fairly strategic position, and the more ambitious 5...cxd6, giving Black more pawns in the center, as Wikipedia describes. 5...Qxd6 is considered inferior.

Plans for White

Develop with Nc3, Be3 and Nf3 or Ne2, and keep the space the c4 and d4 pawns give. In the 5...cxd6 lines, White often plays Be3, Rc1 and b3 (the Voronezh Variation) to keep a grip on the center.

Plans for Black

Develop with ...g6, ...Bg7 and ...O-O, or ...Be7 after ...exd6, and hit d4 with ...Nc6 and ...Bg4. Black's pieces can build pressure on d4, and ...e5 or ...d5 breaks free.

Watch out for

For Black, choosing the recapture. 5...Qxd6 is considered inferior, so the choice is between ...exd6 and ...cxd6; each needs the right follow-up.

For White, the d4 pawn. With the e-pawn gone, d4 is White's main center pawn, and Black's pieces can target it.