Comparable homes are selected for the home that you searched for from among the set of homes that have sold in the past year and are within one mile of the subject home (these two criteria are expanded until a sufficient number of comps are identified). Among all homes meeting these initial criteria, the comparable homes are sorted by their similarity to the subject home on the basis of a number of attributes such as the distance from the subject home, sale date, number of bedrooms, number of bathrooms, the year the home was built, square footage of the home, and size of the lot. Please see Zillow’s site for a more detailed overview of comparable homes.