In an Agile approach, requirements and solutions evolve through the collaborative effort of self-organizing and cross-functional teams and their customer(s)/end user(s). It advocates adaptive planning, evolutionary development, empirical knowledge, and continual improvement, and it encourages rapid and flexible response to change.

Most agile development methods break product development work into small increments that minimize the amount of up-front planning and design. Iterations, or sprints, are short time frames (timeboxes) that typically last from one to four weeks. Each iteration involves a cross-functional team working in all functions: planning, analysis, design, coding, unit testing, and acceptance testing. At the end of the iteration a working product is demonstrated to stakeholders. This minimizes overall risk and allows the product to adapt to changes quickly. An iteration might not add enough functionality to warrant a market release, but the goal is to have an available release (with minimal bugs) at the end of each iteration. Multiple iterations might be required to release a product or new features. Working software is the primary measure of progress.

Iterative, incremental, and agile approaches work well for projects that involve new or novel tools, techniques, materials, or application domains. They also work well for projects that:

• Require research and development
• Have high rates of change
• Have unclear or unknown requirements, uncertainty, or risk
• Have a final goal that is hard to describe.

By building a small increment and then testing and reviewing it, the team can explore uncertainty at a low cost in a short time, reduce risk, and maximize business value delivery. This uncertainty may be centered on suitability and requirements, technical feasibility and performance, or process and people.

The Agile Manifesto

In 2001, seventeen software developers met and developed The Agile Manifesto which has and shaped the agile movement

We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value:

• Individuals and interactions over processes and tools
• Working software over comprehensive documentation
• Customer collaboration over contract negotiation
• Responding to change over following a plan

That is, while there is value in the items on the right, we value the items on the left more.

The Manifesto for Agile Software Development is based on twelve principles:

• Customer satisfaction by early and continuous delivery of valuable software
• Welcome changing requirements, even in late development.
• Deliver working software frequently (weeks rather than months)
• Close, daily cooperation between business people and developers
• Projects are built around motivated individuals, who should be trusted
• Face-to-face conversation is the best form of communication (co-location)
• Working software is the primary measure of progress
• Sustainable development, able to maintain a constant pace
• Continuous attention to technical excellence and good design
• Simplicity—the art of maximizing the amount of work not done—is essential
• Best architectures, requirements, and designs emerge from self-organizing teams
• Regularly, the team reflects on how to become more effective, and adjusts accordingly

"What is Agile Software Development?". Agile Alliance. 8 June 2013. Retrieved 4 April 2015.

Kent Beck; James Grenning; Robert C. Martin; Mike Beedle; Jim Highsmith; Steve Mellor; Arie van Bennekum; Andrew Hunt; Ken Schwaber; Alistair Cockburn; Ron Jeffries; Jeff Sutherland; Ward Cunningham; Jon Kern; Dave Thomas; Martin Fowler; Brian Marick (2001). "Principles behind the Agile Manifesto". Agile Alliance. Archived from the original on 14 June 2010. Retrieved 6 June 2010.

Agile Practice Guide, Project Management Institute, 2017

www.agilemanifesto.org