Using Agile development for your Web Application allows your organisation to build what your users need and not what you think your users need.
Testing is very much integrated in agile development. Incorporating continuous integration and daily testing into the development process, allowing the development team to address issues while they’re still fresh.
Delivering your product quicker and more often with every release. You get early access to your web app during the life cycle.
By focusing features on the needs of real customers, each feature incrementally delivers value, not just an IT component. This also provides the opportunity to beta test software after each iteration, gaining valuable feedback early in the project and providing the ability to make changes as needed.