A software development lifecycle (SDLC) model is a structured approach that outlines the stages involved in developing software applications. It typically includes phases such as planning, requirements gathering, design, development, testing, deployment, and maintenance. Each phase plays a crucial role in ensuring the final product meets user expectations and quality standards. Employing an SDLC model helps teams manage project complexities, adhere to timelines, and improve collaboration among stakeholders by providing a clear roadmap for the development process.