Development phases refer to the distinct stages that a project or product goes through from conception to completion. These phases typically include planning, design, implementation, and evaluation. Each phase has specific goals and tasks that help ensure the project progresses smoothly and meets its objectives. In the context of software development, for example, the waterfall model outlines a linear approach where each phase must be completed before moving on to the next. Alternatively, agile methodologies promote iterative development, allowing for flexibility and continuous improvement throughout the project lifecycle.