The power of exploiting and taking your opponents weaknesses.

everything is both a weakness and a strength, depending on the circumstances. An isolated pawn is a strength in some positions and can be a great attacking asset, but is a fatal weakness in others. While writing a Lichess study of the Bird Opening, I discovered an interesting game by Bent Larsen against a lesser-known teacher, Leon Piasetski.
In the Leningrad variation of the Dutch and the Birds Opening, you will play your pawns at g3 / g6, f4 / f5, and d3 / d6 in the opening moves: this creates an obvious hole on e3 / e6. The player leaves it there in the hopes of achieving an e2-e4 / e7-e5 thematic push in one move, rather than playing e3 / e6 and then e4 / e5 to fill the hole, which is less risky but does waste time.
To talk about the Bird Opening to save time, Black can anticipate this e2-e4 maneuver with d5-d4, giving White a backward central pawn in second rank. This is a severe weakness because a lagging pawn is difficult to move, and immobility brings many weaknesses in a game of chess. The fact that the pawn is immobilized in the center, deep in White's position, denies White the space to develop and organize his pieces. Here is an example of position: