SANTA MONICA, Calif. — Selling a movie used to be a snap. You printed a poster, ran trailers in theaters and carpet-bombed NBC’s Thursday night lineup with ads.

Today, that kind of campaign would get a movie marketer fired. The dark art of movie promotion increasingly lives on the Web, where studios are playing a wilier game, using social media and a blizzard of other inexpensive yet effective online techniques to pull off what may be the marketer’s ultimate trick: persuading fans to persuade each other.

The art lies in allowing fans to feel as if they are discovering a film, but in truth Hollywood’s new promotional paradigm involves a digital hard sell in which little is left to chance — as becomes apparent in a rare step-by-step tour through the timetable and techniques used by Lionsgate to assure that “The Hunger Games” becomes a box office phenomenon when it opens on Friday.

While some studios have halted once-standard marketing steps like newspaper ads, Lionsgate used all the usual old-media tricks — giving away 80,000 posters, securing almost 50 magazine cover stories, advertising on 3,000 billboards and bus shelters.