Define the major strategies for creating special effects.?

What will be an ideal response?

ANSWER:
Early audiences were easy to fool with simple stop-action effects. Later, the actors were filmed against the backdrop of another film projected from behind, called rear projection. Front projection, compositing, and mattes, along with scale models are still used today. Now, the computer has taken over in special effects. Computer-driven cameras are used for filming multi-layered scenes, and computer animation is added to a film, or is used in entire movies. The real computer revolution in Hollywood is taking place behind the scenes, during the postproduction process.