전세 is a unique rental system in South Korea where tenants pay a large sum of money upfront, known as a deposit, instead of monthly rent. This deposit is typically returned to the tenant at the end of the lease, which usually lasts for two years. During this period, the tenant can live in the property without paying additional rent. The landlord uses the deposit to invest or earn interest, while the tenant enjoys the benefits of living in a home without ongoing rent payments. This system is popular due to its financial advantages for both parties, making it a common choice in the South Korean housing market.