The SDLC, or software development lifecycle, includes the software testing life cycle (STLC). Both are complex, have their own stages, and are closely interconnected since planning testing often occurs in parallel with planning development. Following the SDLC and STLC in parallel allows you to prevent dysfunction and errors at the early stages of development by providing flexibility and constant communication. It also helps to save money and time on solving accumulated problems such as defects in module integrations and interface issues.