Scandinavian Defense, Main Line

In this glossary, the Scandinavian Main Line is identified by 1.e4 d5 2.exd5 Qxd5 3.Nc3 Qa5. Black immediately wins back the pawn with the queen. White brings the knight to c3 while attacking that queen, so Black moves it to a5.

The sequence is written in algebraic notation: squares such as e4 combine a column letter and row number; N means knight, B bishop, R rook, and Q queen; pawn moves normally show their destination, x marks a capture, and + marks check. Moves are read in pairs, White first and Black second; dots before a move shown alone indicate Black's turn.

Black's benefit is a clear pawn arrangement and immediate recovery of the pawn. The cost is that the queen moves several times while White brings out a piece with an attack. A move that takes a piece from its starting square to a useful square and forces the opponent to move the same piece again gains a development tempo, meaning one useful move in the race to activate the pieces.

• Black commonly follows with ...Nf6, ...c6, ...Bf5 or ...Bg4, and ...e6. The c6-pawn may provide the queen with a retreat square and support a compact formation.
• White occupies the center with d4, brings out Nf3 and Bc4 or Bd2, and tries to use the lead in active pieces without chasing the queen at any cost.

The queen on a5 is not simply misplaced: it may pressure c3 and influence the a5-e1 diagonal while Black brings out the remaining pieces. The label Main Line does not mean this is the only important Scandinavian system. The Modern Variation chooses 2...Nf6 and delays the pawn's recovery.