An information and limitations concept describing quantitative bounds and distinguishability measures in quantum systems. It governs tradeoffs between incompatible measurements and how well states or processes can be inferred from finite data. It does not imply experimental impossibility in all cases and must be interpreted alongside the chosen measurement model and noise sources. It materially affects metrology and verification by bounding achievable precision and by quantifying similarity between states. The concept is generally stable, though tighter bounds and operational interpretations are refined over time.