Key ideas
- Black usually does not try to keep the extra pawn. White wins it back with e3 and Bxc4 or with Qa4+.
- In return for the centre, Black gets free development and targets d4 with ...c5.
Plans for White
Recapture on c4, build a centre with e4 or e3-d4, and use the extra central space.
Plans for Black
Develop smoothly with ...Nf6, ...e6 and ...c5, and challenge White's centre before it gets too strong.
Watch out
Holding the pawn with ...b5 often backfires: after 3.e3 b5? 4.a4 c6 5.axb5 cxb5 6.Qf3 White wins material on the long diagonal.