Visual Effects (VFX) refer to the process of creating or manipulating imagery to enhance or alter scenes in films, television shows, video games, advertisements, and other visual media. VFX are used to achieve results that would be impractical, dangerous, or expensive to achieve through practical means during the actual filming or production.

The main goal of visual effects is to create an illusion that seamlessly integrates with live-action footage, making it appear as though the elements or actions captured on camera are real. VFX can range from subtle enhancements to elaborate and fantastical sequences, including:

1. Digital Effects: This category includes various computer-generated elements, such as creatures, vehicles, environments, and objects. These digital elements are created using specialized software and are often integrated with live-action footage.
2. Matte Painting: Matte paintings are static, painted backgrounds or scenes that are combined with live-action footage to create expansive and realistic environments that would be costly or impossible to build or shoot on location.
3. Compositing: Compositing involves combining multiple visual elements, such as live-action footage, digital effects, and matte paintings, into a final, seamless image. This process ensures that all the elements fit together naturally.
4. Motion Capture: Motion capture (mo-cap) is used to capture the movements of real actors and transfer them to digital characters, creating more realistic and lifelike animations for characters or creatures.
5. Miniature Effects: Sometimes, physical miniature models are used to simulate large-scale scenes, such as city destruction or spaceship battles. These miniatures are then filmed and combined with live-action footage.
6. Simulation Effects: This category includes various simulations, such as particle systems for fire, smoke, water, and explosions, as well as cloth and hair simulations for realistic movement.
7. Green Screen (Chroma Key): Green screens are used during filming to replace the background with different images or scenes in post-production. This allows actors to interact with virtual environments or creatures that will be added later.
8. Practical Effects: Though not strictly VFX, practical effects are physical effects created on set without digital manipulation. These can include animatronics, prosthetics, pyrotechnics, and more.

Visual effects have revolutionized the film and entertainment industry, allowing filmmakers to bring imaginative and breathtaking stories to life on the screen. The creation of realistic and seamless VFX requires a combination of artistic creativity, technical expertise, and advanced software tools. VFX artists and studios play a crucial role in modern filmmaking, helping to create immersive and unforgettable visual experiences for audiences worldwide.