Bishops are strongest in endgames with pawns remaining on both sides of the board. This situation allows them to use their long-range capability to its fullest, and minimizes the handicap of only being able to access one color of squares. This is contrasted with the other minor piece, the knight, which excels in endgames where all the pawns remain on one wing because it can cover squares of both colors.
In the somewhat silly diagram above, the White bishop is using its long-range abilities to their full potential. While Black has five connected passed pawns, the White bishop stops all of them in their tracks by controlling the long diagonal. White will win easily by promoting his only remaining pawn.
