In programming, what is a block of organized and reusable code that performs a single action called?

A block of organized and reusable code that performs a single action is called a function. Functions are fundamental concepts in programming that allow developers to encapsulate specific tasks within a defined entity, making code more manageable and efficient. By creating functions, programmers can avoid redundancy by reusing code without having to rewrite it every time the same action is needed.

Functions typically take input parameters, process them, and return an output, which enhances the modularity and readability of the code. This encapsulation ensures that changes or debugging can be limited to the function itself rather than affecting the entire codebase. Functions also facilitate collaboration among developers, allowing multiple people to work on different functions simultaneously without interfering with each other's work.

While terms like module, script, and routine may also relate to organized code in programming, they do not specifically describe the concept of a reusable block that performs a single action, making them less precise compared to the concept of functions.