The software lifecycle defines the complete process by which software is conceived, developed, deployed, maintained, and eventually retired. In the context of modern engineering — particularly for complex systems such as autonomous platforms, embedded systems, or enterprise solutions — understanding the lifecycle is essential to ensure quality, reliability, and maintainability. The lifecycle acts as a roadmap that guides project teams through stages of development and management. Each stage defines specific deliverables, milestones, and feedback loops, ensuring that the software evolves in a controlled, traceable, and predictable way ^[1].

“The software lifecycle refers to a structured sequence of processes and activities required to develop, maintain, and retire a software system.” — ^[2] In other words, the lifecycle describes how a software product transitions from idea to obsolescence — incorporating all the engineering, management, and maintenance steps along the way. The lifecycle ensures:

• Consistency: A common framework for teams and stakeholders.
• Quality assurance: Enables verification and validation at each stage.
• Traceability: Establishes clear relationships between requirements, design, code, and tests.
• Risk management: Provides checkpoints to detect and correct issues early.
• Scalability: Supports integration of multiple teams, technologies, and versions.

In regulated domains like aerospace, automotive, and medical devices, adherence to a defined lifecycle is also a legal requirement for certification and compliance (e.g., ISO/IEC 12207, DO-178C, ISO 26262).

The main lifecycle models, Configuration management and configuration management tools are discussed in the following chapters: