What are Subroutines and Why are They Useful?

A subroutine is a block of code that performs a specific task. It is a self-contained piece of code that can be called by name from other parts of the program to perform its task. Subroutines are also known as functions or procedures.

Subroutines are useful for several reasons:

1. Modularity: 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 many different 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. Efficiency: Subroutines can be optimized for performance, making them faster and more efficient than writing the same code from scratch each time it is needed.
4. Organization: Subroutines help to organize code by grouping related tasks together. This makes it easier to understand what the program does and how it works.

In summary, subroutines are reusable blocks of code that perform a specific task, they allow for modularity, efficiency, and organization of code, making it easier to understand, maintain and optimize programs.