In the broadest sense, a database is anything that stores data. A phone book, for instance, could be considered a database as it stores related pieces of information such as name and phone number. However, in the world of computers, a database usually refers to a collection of related pieces of information stored electronically. Aside from the ability to store data, a database also provides a way for other computer programs to quickly retrieve and update desired pieces of data. The central concept of a database is that of a collection of records, or pieces of knowledge. Typically, for a given database, there is a structural description of the type of facts held in that database: this description is known as a schema. The schema describes the objects that are represented in the database, and the relationships among them. There are a number of different ways of organizing a schema, that is, of modelling the database structure: these are known as database models (or data models). The most common model for a database is a relational model. These databases are organized by fields, records, and tables. A field is a single piece of information; a record is one complete set of fields; and a table is a collection of records. With this simple model, just about any relationship between any collection of data can be represented.
