The Saragossa Opening is a chess opening defined by the opening move: Since White usually plays more aggressively in the opening, the Saragossa is considered an irregular opening, classified as A00 by the Encyclopaedia of Chess Openings.
The opening of 1.c3 seems at first to be an unambitious move. It opens a diagonal for the queen, but it makes only a timid claim to the center. It prepares to play d4, but White could simply have played that move immediately. Also, the pawn on c3 has the apparent disadvantage of taking the c3-square away from the knight. It is not a terrible move, however, because it is likely to transpose into many solid systems, including a reversed Caro-Kann Defence or Slav Defense ; the Exchange Variation of the Queen's Gambit Declined, after 1.c3 e5 2.d4 exd4 3.cxd4 d5; to a solid but passive type of Queen's Pawn Game after 1.c3 Nf6 2.d4 or 1.c3 d5 2.d4; or to a reversed Scandinavian Defense after 1.c3 e5 2.d4 exd4 3.Qxd4!? Nc6 4.Qa4; as well as the Ponziani and Center Game openings, to name just a few. Black has a number of responses, the most common being 1...d5, 1...e5, and 1...Nf6. After 1...d5, White can essay the Plano Gambit, 2.e4?!, in effect an unusual response to the Scandinavian Defense. After 2...dxe4, 3.Qa4+ recovers the pawn, but Black getsquickdevelopment with 3...Nc6 4.Qxe4 Nf6 5.Qc2 e5. Also reasonable is 1...f5, when 2.d4 transposes into a Dutch Defense where White has played the passive move c3. The reply 1...c5 is also playable, but gives White more opportunity than other moves to transpose into standard openings where he may have a small advantage. The move 1...c5 2.e4 transposes into the Alapin Variation of the Sicilian Defence. The sequence 1...c5 2.d4 is also possible, when 2...cxd4 3.cxd4 d5 transposes into a regular Exchange Variation of the Slav Defense, which gives White a slight advantage. The move 1...Nc6 is also possible, as it transposes into the 1.Nc3 system, where Black embarks on a rather dubious plan with c6 and d5. After 2.d4 d5, Black seems to be holding the admittedly unusual position without particular difficulties.
