Korea has two address systems, which can be confusing for newcomers: the road-name address and the older lot-number (jibun) address.
Road-name address
Structure: Province + City/District + Road name + Building number. Example: Teheran-ro 152. This has been the official system since 2014 and is best for navigation and delivery.
Lot-number address
Structure: Province + City + Neighborhood (dong) + Lot number. Example: Yeoksam-dong 736-1. It is based on land parcels and is still used in real-estate contexts.
Which to use for shipping?
For international shipping and online shopping, use the road-name address converted to English. Its structure (street name + number) matches international address formats. The converter shows both road-name and lot-number English forms so you can pick what a site requires.
Building number logic
Building numbers are assigned along the road at roughly 20m intervals, with odd numbers on one side and even on the other. So similar numbers are physically close.