By default, no date is entered.
If you want your users to access a campaign from a fixed date, you can enter a campaign start date. Similarly, if your offer ends on a fixed date and you don't want your users to use this campaign after that date, you can enter an end date.
You have several possibilities to postpone the start or stop of a campaign via the archiving or the withdrawal of the teams working on it, for example. The advantage of this menu is that you can do it beforehand so as not to forget D-Day.