What is keyword auto for in C?

C programming language uses storage classes to “describe the features of a variable/function”. These features basically include the scope, visibility and life-time which help us to trace the existence of a particular variable during the runtime of a program.” There are 4 such storage classes: auto, extern, static, and register.

The auto feature is the “default storage class for all the variables declared inside a function or a block. Hence, the keyword auto is rarely used while writing programs in C language. Auto variables can be only accessed within the block/function they have been declared and not outside them (which defines their scope).”