The Interface Segregation Principle (ISP) is the fourth principle in the SOLID design principles. It states:

"Clients should not be forced to depend on interfaces they do not use."

This means that a class should only implement the methods it actually needs. Large, general-purpose interfaces can become problematic when they force implementing classes to include methods they don't require. Instead, it's better to create smaller, more focused interfaces.

The Problem: A Bloated Printer Interface

Let’s explore this principle using a real-world example: a printer system.