Guerrilla Filmmaking
1. Guerrilla filmmaking refers to a form of independent filmmaking characterized by low budgets, skeleton crews, and simple props using whatever is available. Often scenes are shot quickly in real locations without any warning, and without obtaining permission from the owners of the locations.
Guerrilla filmmaking is usually done by independent filmmakers because they don’t have the budget to get permits, rent out locations, or build expensive sets.
Source: Wikipedia