Renfe is Spain's national railway company, running most regional and high-speed AVE trains on the country's extensive railway system. It's easy to visit the biggest Spanish cities on the AVE train, such as Barcelona, Madrid and Seville.

The Trainline is an international digital platform and mobile app that acts as a one-stop shop for booking train and bus tickets across Spain (and much of Europe). In Spain, the rail market was historically a monopoly held by the state-owned Renfe, but recent deregulation has introduced new competitors like OUIGO Spain and iryo. The Trainline is particularly useful because it consolidates all of these operators into a single search interface, allowing you to compare prices and travel times between Renfe’s high-speed AVE, the budget-friendly AVLO, and the new private entrants on popular routes like Madrid to Barcelona or Madrid to Seville. It supports the use of "Renfe Tarjeta Más" loyalty cards and allows for easy digital boarding passes on your phone. For travelers, it is often preferred over the official Renfe website, which has a reputation for being difficult to navigate and sometimes rejecting international credit cards. By using Trainline, you can view the entire "rail landscape" of Spain in one place, often finding cheaper fares on the newer private lines that you might miss if you only checked the traditional national carrier's booking portal.