Holes on the chess board are weak squares that are empty. The square is weak because no pawns can attack the square, so a piece that settles in this square cannot be easily dislodged by biffing. Pawns of the other color are usually controlling the square, and would protect a piece that arrives into the hole.
An important factor is how many pawns are supporting a piece in the hole. One pawn is strong, two is even stronger. If two pawns, then even if the piece can be exchanged, it will leave a protected passed pawn, which is a winning advantage in the endgame.
Holes can also occur without any enemy pawns providing cover. The file may be open, but a piece lodging in the hole will close the file (assuming it is protected by pawns).
In some cases, a hole can appear without any supporting pawns. A hole can occur between two pawns, in front of an enemy pawn. This is the case of an Invulnerable Knight between Pawns (mainly applies as an advanced strategy for Knights in Rook-and-Knight endgames).
A hole on the 5th rank is quite strong. A strong Knight on the 5th rank is a good Knight.
A hole that is on the 6th rank is extremely strong. A Knight lodging on the 6th is often a game-winning advantage. A Bishop lodging in a hole on the 6th is also extremely string. Sometimes a Rook can also lodge on a square on the 6th, which is also extremely strong. In such cases, even if the dominating piece can be exchanged, the resulting passed pawn is likely to be very strong.
Related Chess Tactics
Read more about these related chess strategies:
- Weak squares
- Protected passed pawn
- Dominating pieces
- Strong Knight
- Positional strategies