A collection of data, arranged for uniform search and retrieval.
The actual form can vary wildly. FlatFiles and CSVs are very simple databases. HierarchicalDataBases are one of the longest-established types of DataBase, with GDBM being a prime example. XMLDataBases are currently flavour of the month for all sorts of reasons. But the most widely used form are RelationalDataBases and their practical offspring PostRelationalDataBases.