The Single Responsibility Principle (SRP) is a fundamental principle in software development that states that a class should have only one reason to change, meaning it should have a single responsibility or job within the application. By adhering to the SRP, each class is focused on performing a specific task or function, making the codebase more modular and easier to understand, maintain, and test. This principle helps avoid code duplication, improves code reusability and enhances overall software design by promoting high cohesion and low coupling between classes.