1. A publication system comprising: a storage module to store first publication data and first demand data, the first publication data describing a first item, and being included in a first publication published by the publication system, and the first demand data including a demand measurement registering a first interaction associated with the first publication data, between a first publication originator and a first publication querier; and a modification module, to access the first publication data and the first demand data from the storage module, to receive second publication data from a second publication originator, the second publication data describing a second item, and is to be associated with a second publication, and to generate first modification data with which to modify the second publication data, the first modification data being generated based on the first publication data, the first demand data and the second publication data.