Using a timeline, you can visualize data along a temporal axis. Timelines complement the spatial view of data on the map by showing where in time the data falls. By plotting the data along a timeline, you can understand its temporal order and discern temporal trends that emerge. When combined with time-enabling a map and using the time slider, a timeline gives a complete view of the temporal data and can enhance contextual understanding.
You can plot data on a timeline if time has been enabled on the layer on the Layer Properties dialog box. This data can have either a single time stamp in which case it appears as points along the timeline, or a start and an end time in which case it appears as a linear time span. Data that does not have a location assigned to it can also be plotted along a timeline. A timeline can contain multiple layers from the same map and unique values in a layer, allowing you to view multiple aspects of the data along the same temporal axis. These layers can be viewed in the same horizontal lane, or in distinct lanes, providing you a matrix you can use to compare features through both time and their category or lane.