A pawn which has no pawns of its own colour on neighboring files is called an isolated pawn. The most common sort of isolated pawn is a d- file pawn known as an IQP. It offers its owner some advantages and disadvantages, and these in turn are the basis for formulating strategies around the isolated pawn.
Advantages that isolated pawn offers include a space advantage, two half open files for the rooks and the possibility of sacrificing it and liberating the power of the pieces. The main disadvantage is that it can’t be supported by a pawn and therefore needs to be defended by pieces.
If you’re playing with an isolated pawn you should keep at least one pair of minor pieces on the board to defend it. If you are playing against it you should keep major pieces on the board and try to exchange minor pieces in order to win it using a pin and a lever (…c6-c5 or …e6-e5 against a pawn on d4). Of course proper blockade is must.
Here are two nice games which illustrate the strategy of playing with and against isolated pawns.
1. Huzman against Aronian in 2010
2. Adersson against Portisch in 1985