Well in all actuality… It depends. But here’s what it basically boils to:

Before digital, you’d shoot your film and your negative would be sent to a lab and this lab would develop it and also make an answer print straight from the negative. They would send both back to you and you would view the answer print to see how your film turned out. With this answer print, you then cut up all the shots and sync up your sound on separate mag tape and then edit on a Moviola or a Steenbeck or whatever. This is usually done with just simple splicing tape and a guillotine splicer.

Once everything is assembled the way you want, you send your negative and your edited answer print to a negative cutter. This person will cut and cement splice the actual camera negative to conform it to your edited print. This is usually done in two rolls named A and B so every even numbered shot is on roll A and every odd numbered shot is on roll B and black leader is in between. It looks like this:

Why do it like this? It helps hide splices between each cut and it helps make higher quality dissolves.

Now that you have your A/B rolls, you send this off to a lab to get an interpositive made. It’s a high quality positive print with all the dissolves and any possible color correction done so this is it or die. If you were a poor student filmmaker, you’d stop here and show your IP at your local film festival and then be forgotten.

Now if you’re a big studio distributing all over the world, you make a negative from the interpositive and this internegative (IN) will be the negative that release prints are made from.