If "The Blair Witch Project" taught us anything, it's that you don't need big budgets or elaborate gore effects to make a great, utterly unforgettable horror movie. You just need a strong premise and a cast dedicated enough to pull off the illusion. Celebrate the 20th anniversary of this found footage classic by learning more about the making of "The Blair Witch Project."

1. Part of the reason "The Blair Witch Project" is so effective is that the actors' reactions of fear are often genuine. For example, directors Daniel Myrick and Eduardo Sánchez would sneak up on their tent at night and shake it suddenly.

2. The actors agreed to remain in-character as much as possible during filming. They used the safe word "taco" for those moments when they needed a break.

3. The movie's ad campaign was notorious for convincing many moviegoers it was actually a factual documentary, to the point that many fans sent sympathy cards to actress Heather Donahue's mother.

4. Much of the material for the ad campaign was taken from deleted scenes from the movie. Originally, the movie was intended to include a closing sequence where a news crew investigates the disappearance of the main characters.

5. Even the actors were led to believe the Blair Witch legend was true during filming. They were only told afterward that it was entirely made up for the movie.

6. "The Blair Witch Project" set a Guinness world record for the highest box office to budget ratio, with the movie earning roughly $248 million on a budget of $60,000.

7. One way the production saved money was by purchasing a video camera at Circuit City and returning it for a refund after filming was complete.

8. Approximately 20 hours of footage was shot in total, with the final film being whittled down to a lean 82 minutes.

9. Maryland-based hunters complained about the 1999-2000 season being ruined because so many fans of the movie were traipsing about the wilderness and scaring away game.

10. In addition to two movie sequels (2000's "Book of Shadows: Blair Witch 2" and 2016's "Blair Witch"), the series' mythology has been expanded in the form of comic books, novels and PC games.

11. A spinoff TV series is currently being developed for Lionsgate's Studio L platform.