Storage classes are used to determine any given variable's memory, location, initial value, and visibility. Storage classes allocate the storage area of a variable to be retained in the memory. Although there are 5 different types of storage classes in C, the register storage class helps in faster execution. Register has more immediate access as the variables are stored in CPU registers rather than the RAM. The variables declared using register storage have no default value and are usually declared in the beginning of the program.