The Time Lords are an ancient race of people who have developed the ability to travel through time. As a species there isn't that much remarkable about them aside from the fact they have two hearts (a binary vascular system) and can "regenerate" if they become injured to near death. Apparently Time Lords can only regenerate 12 times (which gives the 13 incarnations) but the Master found a way to live beyond that. Time Lords CAN be killed and not have a chance to regenerate however.SsilverR said:so what are time lords? and if there's an evil dude screwing with time ... how the hell could he even be stopped?weker said:the master is an evil timelord and the timelords are near extinction, the doctor being one of the last.
Their time travelling technology is in the form of vehicles which have been called TARDIS (Time and Relative Dimensions In Space) mostly by the Doctor at first but it seems all Time Lords use the same acronym. There have been many models and the Doctor's TARDIS has been described as an antique when he aquired it (It is at least 700 years old). TARDISs don't all look like Police Boxes from 1960's England, they can change their appearance to suit the environment in which they land. But the Doctor has never bothered to fix the "Chamelion Circuit" which allows it to do this. Well, he did once, but it was short lived...
There have been several renegade time lords as well as The Master but only The Master has popped up in the new series. When he gains enough power and influence, The Master pretty much is unstoppable and just downright evil. In the old series he was just a renegade who wanted power but the new series has him written as more of an unfortunate victim of the time vortex; he stared into it as a child and went crazy.
The "Last great time war" as it is often referenced in the new series is something that occured between the old and new series and has not actually been televised. You might be better off reading this: http://tardis.wikia.com/wiki/Last_Great_Time_War Basically all the Time Lords, along with the Doctor's home planet of Gallifrey, were wiped out, leaving the Doctor as the only living Time Lord... possibly. Who knows, the Whoniverse is HUGE!