Each database provides unique information from sources such as journals, patents, books, and technical reports. Databases are made up of numerous records . The kind of information found in a record depends on the type of database.
Some databases provide bibliographic information and summaries of an original reference.
Other databases provide full articles. Still other databases provide chemical structure, numeric, chemical reaction, or directory information. Records consist of data fields for each kind of information. Information from the data fields is collected to form an index for each field. For example, the Title Index for a database contains terms from titles of all documents in the database.