Alt-azimuth mountA mount with two axes, one vertical (azimuth) and one horizontal (altitude), like a photo tripod. Intuitive and with no polar alignment, it needs both axes moved to follow an object. In long-exposure imaging the field rotates as the minutes pass.
Equatorial mountA mount with one axis (the right ascension, or polar, axis) parallel to the Earth’s axis of rotation. Once polar aligned, turning that single axis follows the stars, by hand or with a motor. The “German” type, with counterweights, is the most common.
GoToA motorised, computer-controlled mount that slews by itself to objects chosen from its database, then tracks them. After switching on, you align it on two or three bright stars. It saves time, but learning the sky still helps when it gets lost.
TrackingThe motion that cancels the Earth’s rotation to keep an object in view. At the sidereal rate the mount makes one turn in 23 h 56 min, about 15 arcseconds per second. At 200× with a 50° eyepiece, an untracked star near the celestial equator crosses the field in about a minute.