Variables: A letter or symbol used to represent an unknown or changing quantity in an equation, for example

, in the equation y = mx + b, y and x are variables. Variables can also represent different values that can be input into a program or algorithm to produce different results. In computer programming, variables are often used to store data or information that can be accessed and manipulated throughout the program's execution. The value of a variable can change over time, depending on the input or output of the program.