Trains are probably the fastest and most comfortable means of transportation in South Korea. Most of the time they are faster than buses are they cannot get stuck in traffic, and they are also faster than planes in that train stations are usually in downtown areas rather than in suburbs. There are also plenty of train options for traveling within a city or a metropolitan area, such as subways and suburban trains. For tourists however riding trains in South Korea can be overwhelming given the number of train services available, the different operators, and the different booking processes. This post summarizes all you need to know to book and ride trains in South Korea.
Intercity Train Services
There are several types of intercity train service in Korea. From fastest to slowest (and most expensive to cheapest): KTX & SRT, ITX & 새마을, 누리로 & 무궁화. Most services (except the SRT) are run by Korail (코레일), a public company.
The different train services run by Korail (all but SRT) and SR (SRT) (adapted from https://flytoazuresky.tistory.com/602?category=669623)
KTX, for Korea Train eXpress, is the fastest transportation link between most cities in South Korea. Two classes of service are available, first class and economy, with economy class being usually 20% to 30% cheaper than first class. First class offers more legroom than the already excellent legroom in economy, so the higher ticket price may be hard to justify. Standing tickets can also be booked; these tickets do not have assigned seats and require standing if no seats are available. They are not drastically cheaper than economy tickets (5% to 15% cheaper) and are probably best booked when there is no stop between your origin and destination stations (such as 광명역 – 대전역).
KTX tickets can be booked in English on the Korail website. They can also be bought directly at any Korail station, such as 서울역 (Seoul station) or 용산역 (Yongsan station) in Seoul.
SRT is another train service run by a sister company of Korail. While KTX lines originate mostly from 서울역 or 용산역, SRT service originates from 수서역 in 강남구. SRT service map does not have as many stations as the KTX service, but trains travel at similar speeds (수서 - 부산 in 2 hours 25 minutes) for similar prices. SRT may thus be a better option if you are traveling from areas surrounding 강남. A lot of Korean people do not know about SRT since it is a relatively new service (2016), so be aware of this option when booking your train itineraries.
Learn about other train services in South Korea by reading the full post.
Metropolitan Train Services
Most major cities in Korea have an independently-run metropolitan train service, usually a mix of underground and overground trains, that connects the city center(s) to the suburban areas. These are different from intercity train services in that, in most cases, tickets do not need to be purchased in advance; instead, passengers need to tap their T-money cards onto the card readers before boarding their train. This includes the Seoul Metropolitan Subway, the Busan Metro, and the Daejeon Metro. Learn more about the different options to get around Korean cities by reading the full post.