Several different techniques are useful to this end. Trailers are assemblies of excerpts from the movie that are shown prior to other movie showings. Advertisements in newspapers, on television, and movie-specific websites can also help. Among the more questionable practices are movie junkets, reliance on so-called quote whores and (allegedly) fake movie fan websites.
As of year 2000, the movie industry spends around $2 billion yearly in movie marketing.