What is a parameter in programming?

A parameter in programming is a special kind of variable used in a method or function to allow the passing of information from one part of a program to another. When a function is defined, parameters serve as placeholders for the values that will be supplied when the function is called. This makes the function more flexible and reusable, as it can operate on different inputs without changing its internal code.

For instance, consider a function that calculates the area of a rectangle. The function may have parameters to accept the length and width of the rectangle. When the function is executed, specific values for those parameters are provided, and the function uses these values to perform the calculation. Parameters effectively help in defining the inputs needed for the function’s operation, promoting clearer and more modular code.

The other options do not accurately capture the concept of parameters. A variable that changes in a loop refers to a different construct in programming related to iteration, while an output of a function refers to the result produced after executing a function with given parameters. A constant value in programming is a fixed data value that does not change throughout the program and is not related to the concept of parameters.