Three-tier architecture refers to a type of architecture of information systems (or applications), i.e. the way that the application is divided into what the user sees and uses (the so-called presentation tier) and what is happening in the background on the server side (the application and data tier).
- The Presentation tier - the part of the application which is visible to the user; it enables the input of requirements and the presentation of results. It is dependent on the platform (e.g. web applications, Windows applications, Android applications, etc.). It may therefore be different for different devices or platforms.
- The Application tier (also functional) - the middle layer of the model (middleware), it assures the calculations and operations performed between input-output requirements and data. Also known as the application server.
- The Data tier (also database) - the lowest layer of the model, it ensures all operations with data, i.e. database management system and basic data-base operations for functional storage, selection, aggregation, processing, integrity, and data audit.
The advantage of such an architecture is that it separates the individual layers so that they are not interdependent.
The predecessor of the three-tier architecture is the two-tier architecture (client-server).
The use of three-tier architecture in practice: Three-tier architecture is used by a large number of applications that work with data. Most of the modern enterprise applications, some portal solutions and websites are constructed in this manner. Three- or more layered architecture is the trend nowadays and it is used to create more robust solutions. Its advantage is a more flexible distribution of output between the user device and the server. Additionally, the presentation layer can run also on inexpensive equipment.