What are the central interface of r/3 system with detail?

The central interfaces of SAP's client-server software R/3 are:

1. DatabaseHere the persistent data are stored, e.g. master data about vendors, employees, customers, etc. Programs are also stored in the database.
2. Application serverIt is here the software is executed.
3. ClientThe client is also called the presentation server, which can be SAP GUI running locally on a client machine.

This architecture is compatible with multiple platforms and operating systems, such as Unix or MS Windows.