What is EAI? What are the tools are used? - EAI is Enterprise Application Integration. Tools used are: WebSphere ICS, WebSphere MQ series, WebSphere Application Server, Tibco, Seebeyond, Vitria etc.

What is Integration? - Integration is nothing but integrating different applications softwares like SAP, Oracle, PeopleSoft, Seibel etc. which belongs to different vendors.

How do I connect diferent software which belongs to different vendors? - There is an adapter for each application which helps to interact respective application with the integration broker.

On which techology is integration broker built? - Usually the brokers like WebSphere ICS,WAS are built on J2EE technology.