How DLG and frigate labels shifted

Why were DLG ships described as destroyer leaders, frigates, and later cruisers?

The terms reflect a mix of build designation, mission, and changing US Navy classification practice rather than one fixed ship type.

DLG stood for guided-missile destroyer leader in the build designation. These ships could also be described as frigates in the older cruising sense, while their hull numbers remained in the DLG sequence. The 1975 reclassification moved some DLGs into the cruiser category and renamed ocean escorts as frigates or guided-missile frigates. American terminology consequently moved closer to allied usage. The changing labels show why classification alone is a poor guide to size or combat power.