(en) In the last two decades, the search and matching theory has probably become the most adopted framework to understand unemployment and other important features of the labour market. Several reasons can explain the success of this kind of models: They describe in a relatively simple way the functioning of markets with frictions (where there is no Walrasian auctioneer and the price loses part of its allocative role), they are analytically tractable, they have some intuitive comparative static analysis and, finally, they are consistent with many empirical facts. These characteristics make also clear why many macroeconomic issues are nowadays studied by assuming a matching technology in the labour market. The present thesis follows this avenue and it can be broadly divided in two parts. The first three chapters analyse the interdependences between the product market and the labour market when the latter presents frictions. The fourth chapter scrutinizes the empirical consistency of matching models.