N-Layer N-Tier
All the layers may reside on the same physical computers(server) while the components in different layers communicate via well-defined interfaces. In this type of architecture, there are at least three separate logical parts, each located on a different physical server.
Communication between layers is explicit and loosely coupled. In this, communication between the tiers is asynchronous to support scalability.
BY Best Interview Question ON 15 Apr 2020