Use the Period tab to specify a period of time (for example, "John Smith was resident in Tunbridge Wells from 3rd June 1971 to July 1985").
Use From on its own if you don’t know when the period ended. Use To on its own if you don’t know when the period began. Use both if you know both.
See Simple Date Fields for help on the actual date fields.
Do not confuse specifying a period with specifying a range (see the Range tab).
With fact dates (dates of events or attributes, displayed in the Facts tab of the Property Box), you can optionally also enter a separate sort date.