Databases exist because of the need to change data into information. Data are the raw and unprocessed facts. Information is obtained by processing the data into something useful. A database is a large repository of facts, designed in such a way that processing the facts into information is easy.
A key, or index, unlocks access to the tables. If you know the key, you know how to identify specific records and the relationships between the tables. Each key consists of one or more fields, or field prefix. The order of columns in an index is significant. Each key has a name.
Data are the values kept in the database. Information is processed data.
A database is a collection of tables, also called entities. Each table is made up of records (the horizontal rows in the table, also called tuples). Each record should be unique, and can be stored in any order in the table.
Before the advent of databases, the only way to store data was from unrelated files. Programmers had to go to great lengths to extract the data, and their programs had to perform complex parsing and relating. Accessing the data from files is a challenging task.