• In 3 tier architecture, there are 3 components: Client PC, An Application server and A Database Server.

• The work of server is distributed among application server and database server.

• Application server has the required communication functions.

• The data required by the business logic exists in database server.

• The required data is returned to public servers and then to client PC.

               Figure 1.1: 3 tier architecture

Advantages:

• Improved Data Integrity

• High Degree of Flexibility in deployment platform and configurations

• Improved security

• High Performance and persistent objects

• Architecture is scalable, adding users and resources in future would be easy

• Maintenance and modifications can be done effectively

• Code and data reusability can be achieved

Disadvantages:

• 3 tier architecture is complex compared to 1 tier and 2 tier

• Cost of network maintenance and deployment is greater than 1 tier and 2 tier