The Urzatron is the nickname for the card trio Urza's Power Plant, Urza's Mine, and Urza's Tower all in play, which combine to provide seven mana with three lands. The Urzatron was first printed in Antiquities and has seen print in Chronicles, Fifth, Eighth and Ninth Editions. It was also heavily featured in Masters Edition IV.
"Urzatron" may also be used to describe a deck which uses an "Urzatron" triplet, for example, Mono-White Urzatron is a deck which uses only White cards but plans to assemble the Urzatron to gain a mana advantage.
There is a wide variety of decks across many formats that have used the Urza lands, and with very few similarities between builds. Naturally, the Urzatron lands are an important part of the deck, but to give a better idea of what other cards are used such decks are often named as 'Blank'tron, for example Izzetron.