Integration Testing is a Level of Software testing where individual units are combined and tested as a group
Integration testing is the testing process in Softwaretesting to verify that when two or more modules are interact and produced result satisfies with its original functional requirement or not. Integrated testing will start after completion of unit testing. Software testing engineer is performing integration testing.
Integration testing finds the bugs that occur when two or more models integrated. Main purpose of Integration testing is to identifying the functional, requirement and performance level bugs. When modules not integrated, they perform as per requirement but when they integrated, functional, requirement and performance related issues will occurs due to the integration.
Definition by ISTQB