A variable, often abbreviated as "var," is a fundamental concept in programming and mathematics. It acts as a storage location that can hold different values during the execution of a program. Variables are essential for managing data, allowing programmers to create dynamic and flexible code that can respond to user input or other changing conditions. In programming languages like JavaScript or Python, variables can be declared using specific keywords, such as "var" in JavaScript. They can store various data types, including numbers, strings, and objects, making them versatile tools for developers. By using variables, programmers can write more efficient and organized code.