In 'House', what is Dr. Gregory House's medical specialty?

In 'Sex and the City', what is Carrie Bradshaw's job? Who played Carrie Bradshaw in 'Sex and the City'? In 'Grey's Anatomy', in which city is the hospital located? In 'ER', in which city is the hospital located? Who played Dr. Gregory House in 'House'? Which TV network originally aired 'Friends'? Which TV network originally aired 'Seinfeld'? Which TV network originally aired 'The Simpsons'?