Methods and systems for providing start and stop properties to Semantic Web structured resources and statements are disclosed. The start and stop properties can specify a lifetime during which a resource or statement can be valid. A call or query to one or more resources can return statement data including the start and stop properties for the resources and/or statements. Dates can be specified with the call or query such that the returned resources and statements have lifetimes including the specified dates. Screen images of the data can display subject and object nodes and predicate arcs for the selected dates. A sequence of screen images can display a timeline of nodes and arcs by adding or hiding nodes and arcs to correspond with the start and stop properties of the statements. Tools are provided for the user to navigate through the sequence.