Mockito is a popular open-source testing framework for Java, designed to facilitate the creation of mock objects for unit testing. By enabling developers to emulate the behavior of complex, real objects, Mockito helps streamline the testing process, allowing for more efficient and effective testing strategies. Its simple API makes it easy to use, even for developers who are new to mocking. Mockito's capabilities include verifying object interactions, stubbing method calls, and mocking interfaces, promoting better code coverage and bug detection.