What is the difference between unit testing and integration testing in software testing?

Unit testing is a type of software testing where individual units or components of a program are tested in isolation. The purpose of unit testing is to validate that each unit of the software works as expected. Unit testing is typically done by developers during the development phase.

Integration testing, on the other hand, is a type of software testing where different units or components of a program are combined and tested as a group. The purpose of integration testing is to test how well different units work together when integrated. Integration testing is usually done after unit testing and before system testing.

In summary, the main difference between unit testing and integration testing is that unit testing focuses on testing individual units or components, while integration testing focuses on testing how well different units work together.