Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Bc5/4. c3/4...Nf6/5. d3

= Giuoco Piano: Giuoco Pianissimo Variation = This is the most popular variation. White opens up the bishop and defends e4. Often the light-squared bishop will move to b3, the knight on b1 to d2, the dark-squared bishop to e3 or g5, and kingside castling. Sometimes a4 and b4 thrusts occur as well.

The most popular continuation, 5...d6, is a common move in the Giuoco Piano, with similar reasons as white's 5. d3. The light-squared bishop often comes to e6 or g4, the dark-squared bishop either stays on c5 or sometimes goes to b6 or a7, and Black castles kingside. If Black attempts h6 and g5, she usually castles queenside. Often a6 is played.

5...a6 is also similar and often transposes to main lines of the Pianissimo. The same goes for 5...O-O and 5...h6.

Theory table
'''1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 Nf6'''