What Is Middleware in Programming?

Software that runs between a request and its final handler to add shared behavior such as logging or authentication.

In practice, middleware becomes easier to use when you trace the input, the state it affects, and the output another part of the program can observe.

Use middleware in a small example first, then vary one input and explain the resulting behavior before you run the code.

Remember middleware as a specific relationship in a program, not as an isolated definition to memorize.