The crew list is a document with the details of everyone who will be on board during your charter. What exactly it has to contain depends on the charter company and on the rules of the country you sail in.
Why the charter company needs a crew list
Charter companies have to register everyone on board with the local authorities. That is why they ask for the crew list before your trip.
The list also matters in an emergency: it tells the authorities and rescue services exactly who is on the boat.
Do hired crew go on the crew list?
If you hire extra crew such as a chef or a host, they do not need to be on your crew list. They do count towards the number of people on board, though, and the boat must not carry more people than it has berths for.
Upload the crew list early
Upload the complete crew list as early as you can, so the charter company can prepare the paperwork before you arrive. If information is missing on the day, check-in can be delayed.
Where to upload it: Where can I upload my crew list, ETA, and skipper licenses? If people join or leave during the trip, see If my crew will change throughout the trip, should I only add the permanent crew to the list?