Three-Tier Architecture

Definition - What does Three-Tier Architecture mean?

Three-tier architecture is a client-server architecture in which the functional process logic, data access, computer data storage and user interface are developed and maintained as independent modules on separate platforms. Three-tier architecture is a software design pattern and a well-established software architecture. Its three tiers are the presentation tier, application tier and data tier.


Techopedia explains Three-Tier Architecture

Three-tier architecture is the fundamental framework for the logical design model.


The essential components within three-tier architecture are:

  • Client PC
  • Application server
  • Database server

Three-tier architecture allows any one of the three tiers to be upgraded or replaced independently. The user interface is implemented on a desktop PC and uses a standard graphical user interface with different modules running on the application server. The relational database management system on the database server contains the computer data storage logic. The middle tiers are usually multitiered.

The three tiers in a three-tier architecture are:

  1. Presentation Tier: Occupies the top level, displaying information related to services available on a website. This tier communicates with other tiers by sending results to the browser and other tiers in the network.
  2. Application Tier: Also called the middle tier, logic tier, business logic or logic tier, this tier is pulled from the presentation tier. It controls application functionality by performing detailed processing.
  3. Data Tier: Houses database servers where information is stored and retrieved. Data in this tier is kept independent of application servers or business logic.

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