Mob Programming is a development practice where the whole team works on the same thing, at the same time, in the same space, and on the same computer. It is a whole-team approach to doing all the work the team does including designing, coding, testing, and working with the customers, users and other stakeholders.
This is an evolutionary step beyond pair programming, and accentuates face-to-face communication, team alignment, collaboration, and self-organizing team concepts of the Agile approach to software development.
Even more, it provides an opportunity to extend the team and involve everyone who is part of the software creation effort such as product experts and customers, technical specialists, and all interested people. Mob Programming can be a highly effective approach to software development.