Kingside

A file is a vertical line of eight squares, identified by a letter from a through h. The kingside contains the e-, f-, g-, and h-files. It is named for the kings, which begin on the e-file in the traditional starting position.

From White's viewpoint, the kingside is on the right; from Black's viewpoint, it is on the left. The term refers to the same squares for both players, so it does not simply mean “my right side.” The sector keeps its name even after the kings move elsewhere.

Castling and play on this wing

Castling is a special move involving the king and a rook. In kingside castling, also called short castling, the king finishes on the g-file and the rook on the f-file in traditional chess.

A phrase such as “kingside attack” describes play concentrated on these four files. A “kingside pawn majority” means that one side has more pawns than the opponent in that sector.