Physically obstructing a square or path.
Why it matters
Blocking is putting a piece in the way on purpose. It answers a check, stops a pawn, or takes an escape square away from a king — the whole idea is that a square stops being empty.
It is also the third answer to a check that beginners forget. Move the king, capture the checker, or block the line: the third one is often the best, because the blocking piece can arrive doing something useful.
See it on a board
The check on the a5–e1 diagonal is answered by blocking on c3 — and the block is a developing move, so the check has cost Black time rather than White.
Checked: the position really has the feature described.
How to play it
- When checked, list all three answers before choosing: move, capture, block.
- Prefer the block that develops a piece or defends something, so the forced move is not a wasted one.
- Check that the blocking piece is not simply captured, and that it is not needed elsewhere.
At each level
The same idea, said the way it is taught at each age.
Bishop · ages 5–7
When the king is in check, you have three choices: move it, take the checker, or put something in the way. Look at all three before you touch anything.
Rook · ages 6–9
The best block is one that also develops or defends. A block that just sits there gives the attacker another free move.
What goes wrong
- Always moving the king when a block would have kept the position together.
- Blocking with a piece that was doing an important job somewhere else.
Questions people ask
- Can you block a check from a knight?
- No. Knights jump, so there is no line to interpose on. Against a knight check you must move the king or capture the knight.