As per companies there are varies phase available for STLC, there is no fix stander for it, but most common phases as per following:
1. Requirement gathering And Analysis: Analyse and review the project requirement and design.it good to start testing activity from requirement phase. Because it will reduce the defect cost.
2. Test Plan: Once you understand the requirements then you will get the idea what u need to test, which strategies, method and environment will be used and which resouses are available.
3.Test Design: You can design the test cases or test scripts depend upon the projects requirements and designs. Create test cases depend upon positive and negative scenario and your imagination.
4. Test Execution: Execute the test cases or test script in setup environment. Defect are reported in bug tracking system after test execution.Testing is iterative process, testing have to be done after every bug fixing.
5. Test Report: Test execution report are created and passed to stakeholder. Final test test document and report prepared in this phase.