Abstract: A database system which uses a hierarchical structure of data nodes. The nodes are of two types, tag nodes forming the hierarchical structure, each tag node having one or more data storing audit nodes as children. Data entered into the database is stored in the audit nodes and changes to the stored data are made by the addition of new versions of the audit nodes such that the audit nodes form an audit trail for the database. Current data is viewed by supplying via the tag node the most recently added child, and older versions of the database are similarly supplied via the tag nodes transparently presenting older versions of the time-stamped audit nodes. The tag nodes may store data which has been automatically deduced from the data in the audit nodes. Both data and the data structure may be selectively replicated throughout the database using an efficient algorithm.