system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What happens between the gap of about the 5 or 6 months when a movie trailer is first released, and the opening theater date?

At this point is it just building hype or is there any strategic way the producers collect feedback and change stuff prior to the release? 

Just curious. 

Thanks!
gpt
Actually in many cases, when you see the trailer, the movie isn't anywhere near done.

It looks like they finished the whole 2 hour movie and you're seeing a selection of 2 minutes of it.

In reality, they might have 200 hours of footage and they're nowhere close to editing it down to a cohesive film. They haven't finished figuring out the soundtrack, the postproduction / visual effects, they might not even know which ending to pick.

There have been lots of cases where the trailer shows a scene that doesn't end up being in the final movie.