The Application Lifecycle refers to the stages an application goes through from initial concept to retirement. It typically includes phases such as planning, development, testing, deployment, and maintenance. Each phase is crucial for ensuring the application meets user needs and functions effectively. During the lifecycle, various tools and methodologies, like Agile or DevOps, may be employed to enhance collaboration and efficiency. Regular updates and monitoring are essential in the maintenance phase to address bugs and improve performance, ultimately leading to the decision to retire the application when it no longer serves its purpose.