Typically a small camera perched on a table or clipped onto any available stable object webcams are useful little devices when it comes to video calls or taking pictures. Due to the fact that they were used regularly for video chat they have built in mics so you can talk directly at it.
Webcams have come a long way from the basic camera they used to house and are now able to stream in high definition or even 4K video! A lot of airports and security offices use them to take images of people as they pass security desks, the small size and ability to control them from a software on the computer make it efficient with larger numbers of people.
People also use them as a means to keep an eye on a space akin to a security camera. Some software can also be controlled through gestures where the webcam acts like an eye for allowing the user to interact with games. They are also used to stream on platforms like YouTube due to which there are models that have mini ring-lights built around the camera so one's lightings needs are also met! Most if not all cheap webcams come with built-it ASIC to do video compression in real-time and are usually connected through a USB cable to the computer. Webcams have good quality despite their low manufacturing cost.
Due to security risks regarding hacking it is recommended that one disconnect their webcam or cover it when not in use as no one would want to be spied on. Made by multiple brands and available in many different shapes colours and designs webcams can be bought at relatively low prices for the work they do. Some of the well-known brands are A4Tech, Microsoft, Logitech and Razer.