The document discusses the Software Development Life Cycle (SDLC) and different types of SDLC methodologies. It describes the Waterfall, Agile, Iterative, and DevOps methodologies. The Waterfall model follows each phase sequentially from planning to deployment and maintenance. Agile prioritizes customer needs and feedback through iterative cycles. Iterative development creates initial versions and improves them through small iterations. DevOps integrates operations into the development cycle to improve usability.