Regression Test is nothing but the test script of the present version is executed on the previous version, to check that the functionality of the present release also works same as in the previous release
Integration Testing, ensures that to check the interface connectivity between the modules and application and to check there is no gap in data flow.
System Testing, All combined modules are tested unitedly if all the modules met the requirements. This testing is done after the coding is completed.
Stress Testing, Tests that provide a high degree of activity, either using boundary conditions as inputs or multiple copies of a program executing in parallel as examples.