and other promotional advertisements. One of the responsibilities of a publicist is to secure permission for and to supervise the placement of these advertisements. This can include anything from putting up posters in theaters around town to securing radio spots nationally. This is really the most obvious of a publicists responsibilities and it's probably the job that the public notices the most. They just don't usually know who's behind those flashy ads that convince them to see the movies.
The publicist also acts as a liaison with the press. They're to go-to-guy (or girl) when it comes to dealing with the press. It may not be particularly glamorous, but hey, someone's gotta do it. Who knows, the press may be kind of cool when you're not a famous person. Probably not, but maybe. The publicist additionally supervises the generation and distribution of press releases. I'm not totally sure how that's different from the first point in this paragraph, but it was two separate bullet points on this article I'm reading, so it's got to be its own substantial point. Right? Ah, who cares?
The last main responsibility of a film publicist is to assist in fundraising activities. This can involve crowd funding (such as IndieGoGo and GoFundMe) or outreach (begging rich people for money, but with class, of course). The publicist works with the executive producers in this step of their job. So basically they work with rich people to get more money from other rich people. It's actually a pretty ingenious setup if you think about it. It seems to work pretty well, at least.
Without publicists, there would be no films. Well, there would be films, but no one would go to see them, considering no one would know anything about them...or the fact that they exist. So they may as well not exist. That's what publicists are for! (Letting us know what's out there and why we "should" see it.)