Microsoft SharePoint Portal Server 2003

The following table lists the default databases

Database	Description
Database ending with _Config_db	it stores the entire configuration database for the SharePoint server/farm. Anything pertaining to global configuration and which is set through the SharePoint central administration is stored in this database.
Database ending with _SITE	it stores all the content of a specific portal. It contains the files, web pages, webs, sites, and all inter-related SharePoint infrastructure.
Database ending with _PROF	it stores entire information about User Profiles; it also stores details of what data to gather about various User Profiles.
Database ending with _SERV	It stores data regarding search, notification, and indexing. It stores the gatherer log information as well as the text indexes for the content that is crawled. In fact, it can be easily checked up by right-clicking on any of the database and choosing Properties. In fact, that could be a way to know how much space each function/activity of your portal is taking up