Ruy Lopez Ajedrez", written in 1561. Although it bears his name, this particular opening was included in the Göttingen manuscript, which dates from c. 1490. However, popular use of the Ruy Lopez opening did not develop until the mid-19th century, when Carl Jaenisch, a Russian theoretician, "rediscovered" its potential. The opening remains the most commonly used amongst the open games in master play; it has been adopted by almost all players during their careers, many of whom have played it with both colours. Due to the difficulty for Black in achieving equality, a common nickname for the opening is "The Spanish Torture".
Four Knights Game attempt for White to exploit the advantage of the first move. In the 1990s, this opening saw a renaissance, and is now seen in the praxis of players from beginner to grandmaster. The Four Knights usually leads to quiet , though there are some variations. The "ECO" codes for the Four Knights Game are C49 (Symmetrical Variation, 4.Bb5 Bb4), C48 (4.Bb5 without 4...Bb4), C47 (4.d4 and others). White's most common move is 4.Bb5, the Spanish Variation. This variation can also be reached from the Ruy Lopez, Berlin Defence. After 4.Bb5, Black has three major alternatives. The first of these is