enumeration data type.

An enumeration in c

is a set of named integer constant that specify all the permissible value that can  be assigned to enumeration variables  are known as enumerators.

OR

It is  a user defined data type which  provides a  way for attaching names two no their by increasing  compress  inability of the code.

The enum key words automatically enumerates a list  of words by assigning  them values   0 ,  and soon, this facility provides  an alternating means for creating symbolic costant.