Reversibility refers to the ability of a process or reaction to proceed in both forward and backward directions without any net change in the system's state. In thermodynamics, a reversible process is one that can be reversed without leaving any change in the surroundings or the system itself. This concept is often idealized, as real-world processes typically involve some irreversibility due to factors like friction and energy dissipation. In broader contexts, reversibility can also apply to various systems, indicating the potential to return to an original state after undergoing a change.