What are Subroutines in Programming?

A subroutine, also known as a function or procedure, is a block of code that performs a specific task. It is a way to organize and reuse code within a program.

In programming, a subroutine is a piece of code that can be called by name from other parts of the program. When a subroutine is called, it executes its instructions, and then returns control back to the point where it was called.

Subroutines are useful for several reasons:

1. Code organization: Subroutines allow you to break large programs into smaller, more manageable pieces. This makes it easier to understand and maintain the code.
2. Reusability: Once a subroutine is written, it can be used in multiple places within a program. This saves time and reduces the risk of errors, as you don't have to rewrite the same code over and over again.
3. Modularity: Subroutines make it easy to modify or update parts of a program without affecting the rest of the code.
4. Efficiency: Subroutines can be optimized for performance, making them faster and more efficient than writing the same code over and over again.

Examples of subroutines include:

1. Functions that perform calculations, such as square root or trigonometric functions.
2. Procedures that perform specific tasks, such as reading or writing to a file.
3. Routines that handle errors or exceptions, such as error-handling functions.
4. Utility functions that perform common tasks, such as formatting dates or strings.