TreeTag is a personal data manager. It stores information in a hierarchy (the "Tree" part of the name). But unlike other tree-based applications, TreeTag automatically positions items in the tree based on field values (the "Tag" part of the name).
The data items are generally configured to contain several fields. Different types of fields are available, including text, numbers, dates, times and predefined choices. The output format of each field can be defined for group headings, for data item titles and for data item output.
The user configures the base portion of the tree, defining rules that will group the data items into desired categories. The same items can appear in multiple locations, with sections of the tree structure using different fields for grouping or sorting. For example, data items can be arranged by date in one section, by a name field sorted alphabetically in another, and by some other category field in another. This allows the differently organized portions of the tree to act almost like predefined searches.