Here are the databases created at the time of installing SharePoint 2010.
Secure Store database: The Secure Store service application database stores and maps credentials, such as account names and passwords. Prefixed with “Secure_Store_Service_DB_”.
State database: The State service application database stores temporary state information for InfoPath Forms Services, the chart Web Part, and Visio Services. Prefixed with “StateService”.
Web Analytics Staging database: The Staging database temporarily stores un-aggregated fact data, asset metadata, and queued batch data for the Web Analytics service application. Prefixed with “WebAnalyticsServiceApplication_StagingDB_”
Web Analytics Reporting database: The Reporting database stores aggregated standard report tables, fact data aggregated by groups of sites, date and asset metadata, and diagnostics information for the Web Analytics service application. Prefixed with “WebAnalyticsServiceApplication_ReportingDB_”.
Search service application Administration database: The Administration database hosts the Search service application configuration and access control list (ACL), and best bets for the crawl component. This database is accessed for every user and administrative action. Prefixed with “Search_Service_Application_DB_”.
Search service application Crawl database: The Crawl database stores the state of the crawled data and the crawl history. Prefixed with “Search_Service_Application_CrawlStoreDB_’.
Search service application Property database: The Property database stores information that is associated with the crawled data, including properties, history, and crawl queues. Prefixed with “Search_Service_Application_PropertyStoreDB_”.
User Profile service application Profile database: The Profile database stores and manages users and associated information. It also stores information about a user’s social network in addition to memberships in distribution lists and sites. Prefixed with “User Profile Service Application_ProfileDB_”.
User Profile service application Synchronization database: The Synchronization database stores configuration and staging data for use when profile data is being synchronized with directory services such as Active Directory Prefixed with “User Profile Service Application_SyncDB_”.
User Profile service application Social Tagging database: The Social Tagging database stores social tags and notes created by users, along with their respective URLs. Prefixed with “User Profile Service Application_SocialDB_”.
Managed Metadata database: The Managed Metadata service application database stores managed metadata and syndicated content types. Prefixed with ” Managed Metadata Service_”.
Enterprise edition installation adds two more databases:
Performance Point service application database: The Performance Point service application database stores temporary objects, persisted filter values, and user comments. Name Prefix “PerformancePointServiceApplication_.”
Word Automation Services database: The Word Automation Services database stores information about pending and completed document conversions.Name Prefix “WordAutomationServices_…”