Storage Classes
An identifier in program will have attributes like storage class, storage duration, scope and linkage.
C provides four storage classes, indicated by the storage class specifiers.
The four storage-class specifiers can be split into two storage durations: automatic storage duration and static storage duration.
Keywords auto and register are used to declare variables of automatic storage duration.
Keywords extension and static are used in the declarations of identifiers for variables and functions of static storage duration.
Storage Classes:
The storage classes of a variables tells the compiler
The storage area of the variable
The initial value of the variable, if not initialized
The scope of the variable
Life of the variable i.e., how long the variable would be active in the program
