USB computer cameras, commonly known as "webcams," are video cameras that feeds its images in real time to a computer or computer network, often via USB, ethernet or Wi-Fi. USB webcams typically include a lens, an image sensor, and some support electronics, and may also include a microphone for sound. Various lenses are available, the most common in consumer-grade webcams being a plastic lens that can be screwed in and out to set the camera's focus.