The date field in ArcGIS Online can be used to visualize data over time, change styling to display temporal differences, track edits, and display a feature’s date and time in a pop-up. The following article provides excellent tips for working effectively with date and time in ArcGIS Online.

Other articles about using time:

Time Slider in Map Media

Rules for Publishing Date Fields

Date Fields in ArcGIS Online

An Example Map with Time