Usage rights
What the client may do with the footage: where, for how long, and in what contexts.
Usage rights define the permitted use of delivered work along four axes: media (organic social, paid social, broadcast, out-of-home, web), territory (one country, a region, worldwide), duration (six months, two years, perpetual), and exclusivity.
They are separate from the production fee, and conflating the two is the most expensive mistake in freelance pricing. The fee pays for making the thing. Usage pays for the value the client extracts from it. That is why the same two-day shoot can reasonably cost very different amounts depending on whether the output runs on one Instagram account or on television for two years.
Write them into the agreement before the shoot, in those four dimensions, in plain words. A grant that says "full rights" is either you giving away everything or a dispute waiting to happen, depending on who reads it.
Where this comes up
The four axes that define what a client may do with your work, why they're priced separately from production, and the carve-out to never sign away.
Build a rate from the income you need and the days you can actually bill, then price usage separately instead of guessing a number and hoping.
The nine clauses that prevent almost every freelance dispute, why a deposit is a commitment test, and what to do when a client won't sign anything.