An information database in communication with an information application comprises a plurality of marketplaces and a plurality of listings respectively classified within {HEAD ~ the plurality} of {TAIL ~ marketplaces} 
An information database in communication with an information application comprises a plurality of marketplaces and a plurality of listings respectively classified within { HEAD ~ the plurality } of { TAIL ~ marketplaces }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL