Pawn Tension

Pawn tension is a pair of opposing pawns that attack each other — either side could capture, but neither has yet. Holding the tension keeps your options open and asks the opponent to commit first; resolving it (capturing, or letting it be captured) fixes the structure. Deciding when, and whether, to release the tension is the whole point.

Source for further study: Watson, Secrets of Modern Chess Strategy (maintaining the tension).