A database is a collection of data that can be accessed by computers. The structure of a database is the way in which the data is organized. There are three types of database structures: hierarchical, network, and relational. In a hierarchical database, data is organized into a tree-like structure. In a network database, data is organized into a series of linked tables. In a relational database, data is organized into tables that are related to one another by means of key values. The most common type of database structure is the relational database. This type of database is easy to use and understand, and it allows for quick retrieval of data.