A Repository is container of information about all the objects and activities done within the tools. it keeps references of remote objects like: Source Data Objects, Target Data Objects, Data Connections, etc. and some of the objects that are created by Informatica Tools are physically kept within Repository like: Mapping Programs and other reusable objects.
Informatica Repository is center point of all the tools and services. Interaction among the tools and services happens through the Repository.
Informatica Repository is physically maintained under a Database System like: Oracle, SQL Server, DB2, etc. while logical parts of the repository are for the Infomatica users and tools.
Repository is also known by the following other names:
1. Data Dictionary
4. Meta Data