This chapter will address the issue of online sales in the fast fashion sector, specifically Zara, the flagship brand of the Inditex textile group. Since 2012, Zara has been working on a plan to close, restructure, and optimize its physical shops, a process that was accelerated in 2017, and which has been affected by the global pandemic that began in early 2020. These two events have caused online sales to exponentially rise with, in turn, the percentage of returns. This is the objective of this chapter: to analyze where Zara is in terms of online sales and returns and how, through digital marketing and the application of tools such as big data, it can reduce the large volume of online returns that it has to deal with.