The "Not Equal Operator" is a comparison operator used in programming to determine if two values are different. It is often represented by symbols like `!=` or `<>`, depending on the programming language. When this operator is used, it evaluates to true if the values being compared are not the same and false if they are equal. For example, in a programming language like Python, the expression `5 != 3` would return true because 5 is not equal to 3. Conversely, `4 != 4` would return false since both values are the same. This operator is essential for making decisions in code, such as in if statements.