FlipSight : Corner, X, C, A and B Squares

Othello strategy starts from the fact that every square has its own character. The squares near the four corners in particular have names.

Green = corner, red = X-square, yellow = C-square, blue = A-square, B = B-square

Corner: the four corners (A1, H1, A8, H8). A disc placed there can never be flipped.
X-square: the square diagonally next to a corner (B2, G2, B7, G7). Playing there carelessly often hands the neighboring corner to the opponent.
C-square: the edge square right next to a corner (B1, A2, G1, H2, A7, B8, H7, G8). Depending on the position, it can give the opponent a way into the corner.
A-square: the edge square after the C-square (C1, F1, A3, H3, A6, H6, C8, F8).
B-square: the two middle squares of an edge (D1, E1, A4, A5, H4, H5, D8, E8).