In South Korea if you are renting you basically have two options for the kind of rental agreement, Jeonse (전세) or Wolse (월세).
This is where a large key deposit is paid to the landlord. The amount is usually well in excess of 50,000,000 KRW ($50,000 US).
Due to the large amount of key deposit paid, no monthly rent is charged.
Legally Jeonse contracts are signed for 2 years.
The Jeonse system is in many ways a great way to save on your monthly expenses as no rent needs to be paid
The tenant only has to pay monthly utility fees (Electricity, gas, water, Etc.)
However, it is vital that you use a trustworthy and reliable real estate agent to check that the landlord doesn't have any unpaid loans, as this could mean that it is difficult / impossible to get your key deposit back.
Wolse is similar to a western rental agreement where there is a smaller key deposit paid and then monthly rent is also paid.
The amount of key deposit varies dependent on the landlord, but still in general they are several million KRW / thousand US $.
The tenent still has to pay monthly utility fees.
Types of Housing
In South Korea there are essentially 5 different types of housing that can be rented:
Officetel - Usually a smallish apartment for one person that is in a building that has both commercial and residential properties.
One-room - the name says it all everything (except the bathroom) is in one (small/very small) room.
Villa - Don't get your hopes up! In the west a villa is usually a large building with its own grounds and maybe a pool. In korea it means an apartment in a building that doesn't go above five floors. These are usually older buildings and may have old window fittings or no elevator.
Apart-uh - Basically an apartment in a high-rise building.
Dan-dok-ju-tek - This is essentially a detached town house with several bedrooms and often a garden. This is a great option for dog owners, and often the landlord will live on the top floor and rent out the bottom floor and basement.