Perrin Variation

After 4. Bd3 White's bishop guards e4 against the pressure from b7. The Perrin Variation answers with 4...Nc6, planning ...Nb4 to remove that bishop and secure the bishop pair, for example 5. Ne2 Nb4 6. Nbc3 Nxd3+ 7. Qxd3. The knight move blocks the c-pawn and costs time, so White keeps a broad center and engines give a slight edge. 5. Nf3 is the most common reply, with 5. Ne2 and 5. Be3 also frequent. White scores well in practice.