Variables play an important role in computer programming because they enable programmers to write flexible programs. Rather than entering data directly into a program, a programmer can use variables to represent the data. Then, when the program is executed, the variables are replaced with real data. This makes it possible for the same program to process different sets of data.
Every variable has a name, called the variable name, and a data type. A variable's data type indicates what sort of value the variable represents, such as whether it is an integer, a floating-point number, or a character.
The opposite of a variable is a constant. Constants are values that never change. Because of their inflexibility, constants are used less often than variables in programming.