In software engineering, a multi-tier architecture is used to describe one in which a degree of separation is attained by one or many software agents between discrete components in order to facilitate processing in some manner. An example of this would be the use of middleware to more efficiently service data requests between a user and a database. May also be referred to as an n-tier architecture. The most widespread use of this term refers to the three-tier architecture.

See also: client-server, three-tier (computing), business logic