These are predefined, human-readable, and understandable words or letters that are used to store some values. At the very basis of writing a program we need a variable in which we will store the data or information, and based upon the variables, we can further enhance the programming logic. As we can see in the first line, an important part of creating a variable is that it should be human-readable and understandable.

Let us take an example: Suppose I want to store a number 2 in a variable. We can choose any name for a variable and define it:

Option 1: x=2
Option 2: number=2

The correct answer will be Option 2, as we know by the variable name (number) that this variable contains a specific number. As we can see in the preceding example, if we keep on using random ways of defining variables as we would when creating a big program, the complexity would be increased substantially because of the unclear meanings of the variables.

Different programming languages have different ways to define a variable, but the underlying concept of ensuring a variable is human-readable should be the top-most priority of the programmer or program author.