The Dobsonian mount consists of three major parts. Azimuth (side-to-side) motion is provided by a turntable, on top of which sits a large box. Into the upper sides of the box are cut two semi-circular cutouts. Two disks are fixed to either side of the telescope at the balance point, and fit into the cutouts on the box to provide altitude (up-and-down) motion. The various bearing points are lined with several pieces of teflon (typically, although felt is also sometimes used) as a bearing surface.
The entire mount is quite small in comparison to typical star-tracking systems, and can be easily transported. This has made it a favourite of amature astronomers because it can be carried to star parties in the back of a small car and set up in moments. The result has been a fixation with ever-larger telescopes, which would otherwise require huge "traditional" mounts. Whereas a 8" Newtonian would be considered large 30 years ago, today 16" systems are common, and huge 32" systems not all that rare.