Agile Testing is a fast and informal testing process. In simple terms, we can say that it is specified as an advanced and dynamic type of Testing that is performed regularly throughout every iteration of the SDLC (Software Development Life Cycle) by the agile test engineers

Software Development Processs
Principle #8: Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.
What is software sustaining engineer?Sustaining Engineering is a critical team that handles the most difficult customer escalations, resolving software bugs, code defects and other issues, from the kernel all the way up to the highest levels of the open source stack.