Confusion about firm, choice and clearing

I've heard that when you choose your 5 unis, you have to select a firm and an insurance. If you don't meet the requirements on results day, you go to clearing? But what about the other 3 universities you applied to?

Once you choose your firm and insurance your other choices no longer exist. You can only go to your firm if they accept you. If they dont accept you then your insurance choice consider you. If your insurance rejects you then you are placed in clearing and can look at any university who still has spaces. Be aware that leading universities and courses dont enter clearing so if you get rejected by firm and insurance you might not be able to use your other choices.

Your position will be

Firm that is where you go if they accept.
Insurance if firm rejects.
Clearing if both firm and clearing reject