What Is a T Visa?

On the subway the other day, I overheard two people discussing someone who had obtained a T Visa from Immigration. What is this? How can I qualify for this visa?
The T Visa provides immigration protection to you if you are a victim of a severe form of human trafficking. Non-immigrant individuals under a T Visa status are required to have three years of continuous presence in the U.S. or a continuous period of an investigation or prosecution of the acts of trafficking before they can adjust to permanent residency status. Adjustment of status cap is 5,000 per year.