What is the purpose of "unit testing" in software development?

Unit testing serves the essential purpose of testing individual components of code to ensure they function correctly. This practice allows developers to check that each specific piece of the application—often referred to as a "unit," such as a function or method—works as intended in isolation from the rest of the program. By conducting unit tests, developers can identify and fix bugs early in the development process, making it easier to maintain and improve the code over time.

One of the key benefits of unit testing is that it encourages good design practices. When each component is tested individually, it often leads to the creation of more modular and decoupled code, which is easier to manage and test. This also facilitates more efficient debugging, as developers can focus on the specific unit that is failing rather than searching through a larger codebase.

Other options present different testing focuses, such as evaluating overall system performance, ensuring compliance with standards, and verifying integration with other systems, which involve broader scopes beyond individual code components. These practices are important in their own right but do not specifically address the isolation and correctness aspect that is central to unit testing.