Getting around in any of South Korea's major cities is easy and convenient, thanks to the cheap and extensive public transportation system.

As the first segment in a four-part series on South Korea's mass transit systems, this article will review how to transfer between buses, the subway and other forms of transportation.

The transfer system allows passengers to switch between different types of public transport without paying an additional fee.

To avoid paying any extra charges, one should remember three ground rules:

1) Payments must be made with a card (either a T-Money card or an eligible bank card), not cash.

2) Free transfers are allowed up to four times a day, which equals a total of five rides.

3) You must transfer within 30 minutes, although this time limit is extended to one hour between 9 p.m. and 7 a.m. the next day.

However, if a passenger transfers to a more expensive form of transportation, he or she must pay the difference. For example, if one transfers from the subway -- which costs 1,250 won for adults -- to an inter-city bus -- costing 2,300 won -- an additional charge of 1,050 won will be incurred.

Passengers must also pay any additional charges based on distance.

All of these surcharges are applied automatically when you tap your card on the card reader.

When the transfer system was first introduced in Korea in 2001, it was limited to a discount of just 50 won for the next ride. Over the years, the system has expanded to include free transfers between different modes of transport, although different cities and provinces may have their own rules.

For example, Busan's public transportation system also allows for free transfers between buses and the subway within 30 minutes. However, this is limited to only two transfers -- not four like in Seoul. Transfers in Daejeon are limited to three transfers, and transferring between short-distance "maeul" or village buses and the subway requires an additional fee.

Daegu and Gwangju have different transfer systems which allow for an unlimited number of transfers, but only within 30 minutes of boarding the first mode of transportation. This differs from the other three cities where a transfer needs to be made within 30 minutes of getting off the previous means of transportation.

For example, in Seoul, Busan and Daejeon, if one boarded a bus at 1:00 p.m. and got off at 1:20 p.m., he or she could transfer to another bus free of charge before 1:50 p.m. But for Daegu and Gwangju, if one boarded a bus at 1:00 p.m., he or she could transfer as much as one wants before 1:30 p.m. under the free transfer system, but not after that time.

Survive & Thrive is a series offering a guide to living in South Korea for those born outside of the country. – Ed.