IT Mill Toolkit data model is one of the core concepts in the library and Property-interface is the base of that model. Property provides standardized API for a single data object that can be read (get) and written (set). A property is always typed, but can optionally support data type conversions. Optionally properties can provide value change events for following the state changes.

The most important function of the Property as well as other data models is to connect classes implementing the interface directly to editor and viewer classes. Typically this is used to connect different data sources to UI components for editing and viewing their contents.

Properties can be utilized either by implementing the interface or by using some of the existing property implementations. IT Mill Toolkit includes Property interface implementations for arbitrary function pairs or Bean-properties as well as simple object properties.

Many of the UI components also implement Property interface and allow setting of other components as their data-source. These UI-components include TextField, DateField, Select, Table, Button, Label and Tree.