Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Nf6/5. O-O/5...Nxe4/6. d4/6...b5/7. Bb3/7...d5/8. dxe5

=Ruy Lopez Open Defence=

Black must drop everything and defend the d-pawn from the threat uncovered by dxe5. 8...Be6 does this while also developing and stabilising the centre.

For the sake of completeness, 8...Ne7 slows down Black's development to such an extent that White can give up the bishop pair and still have a commanding position, while the horrible 8...d4 pulls the rug out from under the e4-knight while not particularly improving the pawns condition. Absolutely no Brownie points for either of these moves.