In this paper we explore how (micro)economic theory can be used to analyze and model the exchange of information on the Web. More specifically, we consider searchers for information who engage in transactions on the Web. Searchers will engage in web transactions only if they gain something in such a transaction. To this end we develop a formal model for markets, based on the notions of value and transaction. This model enables us to examine transactions on an information market. In this market we have a dual view on transactions, creating a dichotomy of transactors and transactands.