Nextag is an independent price comparison service website for products, travel, and education. It started as a website where buyers and sellers could negotia on comparison shopping. Broad$-$based shopping bots like Nextag

a$.$ are programs that search websites which are based on a Yellow Pages type of model

b$.$ search sites like SeatGeek and Kayak

c$.$ search for prices for only one type of product

d$.$ give pricing power to the retailers