Why are corners so important in Reversi?
If you learn only one thing about Reversi strategy, learn corners. Here is why they matter so much and how to fight for them.
Corners are permanent power
Every other disc on the board can be flipped by a well-placed move, but a corner disc is untouchable - there is no square beyond it to flank from. That permanence turns a corner into an anchor: discs anchored to a corner along an edge become stable too, and stable discs are the ones you actually keep at the end. Fighting for corners on the 8x8 board is the backbone of sound play.
How to take corners - and deny them
You rarely grab a corner by force; you win it because your opponent is forced to give it to you. The key is to avoid the X-squares and C-squares next to a corner yourself, while manoeuvring so your opponent must play one of them. On smaller boards like 6x6 the corner fight starts almost immediately, which makes them great practice for corner technique.
Related questions
How do you win at Reversi?
Winning Reversi comes down to three ideas: grab the corners safely because corner discs can never be flipped; play for mobility by keeping many good moves for yourself and few for your opponent; and control parity so you make the last move in each region. Chasing raw disc count early is usually a mistake.
What are X-squares and C-squares in Reversi?
X-squares are the four cells diagonally adjacent to the corners; C-squares are the cells directly beside a corner along an edge. Both are dangerous because playing them before the corner is settled usually hands your opponent a safe way to seize that corner. Avoiding premature X- and C-square moves is one of the first skills good players learn.
What is mobility in Reversi?
Mobility is the number of good legal moves available to you. Strong Reversi play keeps your own mobility high while squeezing your opponent's down, so that eventually they are forced into bad moves - like giving up a corner. Mobility usually matters far more than how many discs you currently own.