The purpose of a software development lifecycle (SDLC) is to provide a structured approach to developing software applications. It outlines various stages, including planning, design, development, testing, deployment, and maintenance, ensuring that each phase is thoroughly addressed. The SDLC framework helps developers utilize resources efficiently, manage risks, and deliver high-quality products. By adhering to the SDLC model, teams can improve project management, establish clear timelines and deliverables, and enhance collaboration among stakeholders throughout the development process, ultimately leading to successful software implementation.