How are contestants chosen to "come on down" on The Price is Right?

I have been an avid viewer of The Price Is Right for many years. i understand that a person has to request tickets, just to be in the audience. but, from this point on, how is one person selected over another, to “come on down”, to actually play the game? are the names drawn from a hat? it appears that the chosen people are a good cross -representation of the culture mixture of America. so, how do they do it? what makes one person stand out to be chosen over the rest of the audience?