SDLC has six steps. These are requirements gathering, design, development, testing, release, and maintenance.
Product Owner collects the requirements from the client. Then business team writes the SRS - Software Requirement Specification document according to these requirements and uses SMART (Specific, Measurable, Achievable, Relevant, and Testable) criteria.
2. DESIGN
Designers, design a prototype of the software according to the SRS. Then the SDS Software Design Specification document is written in this step.
3. DEVELOPMENT
Developers build/develop the software according to SRS/SDS documents and feedback. There are 4 Software Environments a.Development (Developers)
b.QA/Test (QA Engineer - SDET/Perf. Testers)
c.Staging (Client)
d.Production (End-Users)
4. TEST
Testers, test the app in the QA Env. according to the expected and actual results. If there is a difference between them, they write a bug report.
a. Functional testers test the functionalities of the app on 3 layers (UI, DB, API)
b. Performance testers test the non-functionalities of the app
5. RELEASE/DEPLOY
Developers/Testers/BT release the application then End-Users use it in the production environment.
6. MAINTENANCE
End-Users may find a bug in the application or receive feedback then developers fix and testers test it. It is known as Hotfix.
SDLC starts again with the new requirements. That is why we call it the life cycle.