What is function definition?

Function definition is the process of defining a function or method in a programming language. It is a block of code that is used to perform a specific task or operation. A function consists of one or more statements that are executed as a single unit. Functions can be written in most programming languages and allow developers to reuse code across different parts of their program.

The function definition typically includes the function's name, input parameters or arguments, and a set of statements or instructions that perform the desired task. A function can also have a return value, which is passed back to the calling code.

Function definition in programming serves several purposes such as code reusability, making code more organized and easier to read, and helps break down complex tasks into smaller chunks. Functions also help in debugging and maintenance of the code.

Function definition can be done in several ways depending on the programming language, including writing it inline, in a separate file or module, or sharing it across different programs or libraries. The function definition is an essential building block of any programming language and is used extensively in software development.