Porto is served by a modern international airport, Francisco Sá Carneiro (IATA: OPO).
The airport is served by several international airlines, including low cost alternatives such as Ryanair and Easyjet. For a more detailed list of direct connections please see the airport destinations page or the correspondent wikipedia section.
The airport is located 11Km from the city, and is served directly by a subway station connecting you to the city centre through line E (a ticket from the airport to the city costs 2€ + 0.6€ for reusable Andante card). For more information about the subway check www.metrodoporto.pt. A taxi to the city centre will cost around 20€. For a more detailed list of options to go from the airport to the city check this page.