Voltage regulator ICs are broadly classified into ICs for converting a DC voltage into a required DC voltage and those for converting an AC voltage into a desired DC voltage.
Voltage regulator ICs for DC-DC conversion are further classified into linear regulators and switching regulators also known as DC-DC converters. Linear regulators exist in two basic forms: series regulators and shunt regulators. Low-dropout (LDO) regulators are a type of series regulators.