The development life cycle of a product or a feature is a wide process that includes:
Specifications, which is the conceptual part of the process (technical requirements, task assignments and so on.). For more information, see Specifications.
Development and testing, which is the designing part of the process. For more information, see Developing and Testing.
Deployment into QA and Production environments. For more information, see Continuous Integration: Deploying to QA and Production environments.
Maintenance which is mainly achieved through SVN or GIT branching and tags. For more information, see Maintaining.