A tripod is a three-legged contraption that comes with or without a standard head for supporting a camera system. Most entry-level tripods come with a tripod head built in. But the more expensive ones allow you to buy a separate tripod head as per your choice. Fundamentally, this is a supporting rig for your camera. The legs are telescopic.
Additionally, the legs on some tripod systems can be set independent of each other. This is ideal for uneven surfaces or where you need additional purchase out of the ground for stability. The central column to which the tripod head attaches to and therefore supports the camera system is also telescopic.
Some tripods come with the ability to oscillate the central column by 180 ◦ so that it can point the camera system towards the ground. Additionally, tripods are manufactured in a wide variety of materials. The best ones are usually made of carbon-fiber.