This section explains Space, what it means, why it is important.
Space is the number of squares you attack on the opponents side of the board. Space is generally an excellent measure of who has the better pieces. Mobility is the total number of legal moves a player has.

Look at the squares attacked by white. In contrast black has almost no space on whites side of the board. If you total the piece value for black and white and the space for black and white you will note:
|
Whites Material |
Blacks Material |
|
31 Pawns |
34 Pawns |
|
Whites Space |
Blacks Space |
|
24 Squares |
2 Squares |
|
White Mobility |
Black Mobility |
|
31 moves |
26 moves |
If you did the counting, you might think that I have counted too many squares for white. I have not. Not only have I counted the number of squares but also the number of times a square is attacked. E5 for example is attacked three times, so it is counted three times.
The point to this exercise is that white is down a piece, three pawns = one bishop or knight. But whites pieces are superior to blacks in terms of both mobility and space. You don't need to actually count space and material to find out whose pieces are better. Once you get the idea, you can get a sense of mobility and space at a glance. Now you know what we are talking about when we say, "Whites pieces are better!"