The software development life cycle (SDLC) is a process by which a software product is developed, tested, and then released. The SDLC consists of four stages: The first stage is the planning phase and involves identifying all the requirements. The second stage involves designing the product, including defining its architecture and components. The third stage deals with building the product from scratch or modifying an existing one. The fourth and final stage is deployment, where the final executable code becomes available for use by customers.