A database is a method of storying information on a computer in a way that is easy to search and quick to recover that information when it is needed. Databases can hold many forms of data including text, numbers (whole and decimal) and binary data.
Most industrial strength databases these days use a language called SQL to communicate with them. It was created by IBM and is officially pronounced ‘Sequel’ but is also commonly pronounced ‘S.Q.L’. SQL allows the user to tell the database what information it would like and can be used to produce some complicated queries.
On websites the common databases tend to be MySQL, SQLite and MSSQL (on Windows servers). They are used to store the content of websites, blog articles and product catalogues amongst many other things. They are an integral part of dynamic websites.