What defines a variable in programming?

A variable in programming is best defined as a value that can change based on actions or conditions. This characteristic allows variables to hold different data at different times during program execution, making them fundamental for tasks that require data manipulation and processing.

For example, in a simple program where a user inputs their age, the variable representing age is not constant; it can be updated based on the user's input or subsequent changes throughout the program. By contrast, elements like constants or static values are fixed and cannot be reassigned once defined, which highlights the dynamic nature of variables. This flexibility is crucial for implementing logic and responding to user interactions, allowing for a more responsive and adaptive program structure.