Pre-tensioning is a method of reinforcing concrete structures in which steel strands or bars are tensioned prior to the concrete being poured. The tensioned strands or bars are then embedded in the concrete and remain in a state of tension once the concrete hardens. This creates a very strong bond between the steel and concrete and provides a high level of structural integrity. Pre-tensioning is commonly used in the construction of bridges, buildings, and other large structures where strength and stability are critical.