More space, usually a result of better development and control of the center, gives you room to create an attack and move your pieces to their most effective squares. On the flip side, being cramped means the pieces get in the way of each other and aren't as effective as they can be. At times, if they are still on the back-rank, for example, they can even take away escape squares from the king when it comes under attack.
- In general, the side that is better developed gets more space.
- If you don't have space, you can't use your pieces effectively.
Space advantage is someone who controls the 4 key central squares, or has better control of the 16 central squares. It could also refer to who has more control of the entire board.