Used as a protecting group for aldehydes and ketones in organic synthesis, allowing selective reactions at other functional sites. It is particularly useful in multi-step syntheses where carbonyl groups need temporary masking under neutral or mildly acidic conditions. Stable under basic conditions and many nucleophilic reagents, it helps prevent unwanted side reactions. Commonly applied in pharmaceutical and fragrance industries where precise molecular construction is critical. Can be removed selectively using mild aqueous acid to regenerate the original carbonyl compound.