Agile Methodology is a project management and software development approach emphasizing flexibility, collaboration, and customer satisfaction through continuous delivery of high-quality products or services. Central to Agile is the idea of iterative development, where projects are divided into small, manageable segments known as sprints or iterations.

Teams work through the entire software development cycle, including planning, design, coding, testing, and review, during a few weeks-long iteration.

Agile differs from Waterfall by not requiring the completion of each phase before the next. Agile allows for more frequent reassessment and adaptation of plans, which is critical in a fast-changing environment.

Fundamental principles of Agile include:

  1. Customer Collaboration: Working closely with the customer for better understanding and feedback.
  2. Adaptive Planning: Encouraging flexible responses to change.
  3. Early Delivery: Focusing on the rapid delivery of business value.
  4. Continuous Improvement: Regularly assessing how to become more effective.
  5. Sustainable Development: Maintaining a constant pace and workload to ensure long-term sustainability.

Agile methodologies include several frameworks, like Scrum, Kanban, Lean, and Extreme Programming (XP). Each has its own practices but shares Agile's core principles. This approach has gained popularity across various industries beyond software development.