Is a technique used to test whether the flow of an application right from start to finish is behaving as expected. For anything relating to applying a test, protocol, or other desired action to a set of servers from front-end to back-end.
While testing all of the individual components and connections in large system can help to give confidence in a system overall, ensuring that the expectations of system work together as a continuous entity will provide the greatest confidence in its viability.
Many other concepts also apply on an end-to-end level, such as ensuring that data is encrypted from the moment a user submits it until it reaches a database or other back-end or other similar considerations. Particularly as a multi-tiered infrastructure increases in complexity, so to does the burden of ensuring that the expectations of the system hold true across the various components of the system.
