AREX is a South Korean airport rail link and commuter rail line that links Incheon International Airport with Seoul Station via Gimpo International Airport. The section between the two airports opened on March 23, 2007, and line was extended to Seoul Station on December 29, 2010. Long-distance Korea Train Express high speed trains started to use the line from June 30, 2014, but discontinued service in March 2018 due to low ridership.

Incheon International Airport is the main international airport serving Seoul, the capital of South Korea. It is also one of the largest and busiest airports in the world.