Variable manipulation is a method of specifying or editing variables in a computer program. Variable manipulation can be used to create dynamic content in HTML and programming languages. However, the method can also be used by an attacker, to alter data that a browser sends to a Web server. A variable, in this context, is a string of text symbols and/or numerals that can change, depending on conditions or on information passed to the program.
In mathematics, variable manipulation is the process of rearranging a multivariable equation to express a specific variable as a function of other variables. The variable thus singled-out is known as the dependent variable, while the other variables are called independent variables. In this context, a variable is a mathematical quantity whose numerical value can change, in contrast to constants that have fixed numerical values.