The Layered Architecture (3-tiered, n-tier or multi-tier architecture) is one of the most known and used concepts in enterprise development. It is the de-facto standard for building applications; so much that it would be hard to find a single application in the enterprise software realm that does not conform to it.
Many things changed, however, since the inception of this architecture pattern; there are new ways to organize code and new ways to organize teams and operate software.