What is 'unit testing' in software development?

Unit testing is a crucial practice in software development that focuses on verifying the functionality of individual components or modules within a program. This type of testing is typically conducted by developers to ensure that each part of the code performs as expected. By isolating individual parts of the application, developers can identify and fix issues at the earliest stage possible, leading to more reliable and maintainable code.

The importance of unit testing lies in its ability to catch bugs early in the development process before they accumulate and affect later stages of development or production. It also facilitates code changes and refactoring, as developers can run unit tests to confirm that existing functionality remains intact after modifications.

While other forms of testing, such as integration testing or performance testing, play significant roles in the software development lifecycle, unit testing specifically targets the evaluation of standalone components, ensuring that each works correctly in isolation before they are integrated into the larger application.