Every country has customs and everyday habits that may surprise visitors. Here are ten things you may notice in South Korea. Experiences vary by place and person.
Side dishes and refills

Many Korean restaurants include small side dishes, called 반찬 [banchan], with a meal and offer refills of some dishes at no extra charge. Policies vary, and special items may cost extra. To ask for more, say 더 주세요 [deo juseyo] (“More, please”). You can also name the dish: 김치 더 주세요 [gimchi deo juseyo] (“More kimchi, please”).
Late-night city life

Some nightlife districts in Seoul and other cities remain busy late into the night. You may find convenience stores open around the clock and restaurants or bars with late opening hours, but this varies by neighborhood and business.
Seoul has late-night bus routes. Check the timetable for your particular journey; an intercity bus or subway line may not run all night. A busy street is not a guarantee of safety.
Widely available Wi-Fi

Free Wi-Fi is widely available in cafés, accommodation, and many public spaces, including parts of Seoul’s transport network. Coverage and access conditions vary; not every network is open to every visitor.
Seoul operates public Wi-Fi hotspots in places such as parks and busy streets. Ask staff for the network name and password when using a café or hotel connection.
Masks and air-quality vocabulary

You may see people wearing masks for several reasons, including air pollution, respiratory symptoms, or personal preference. Mask use does not by itself tell you whether someone is ill.
황사 [hwangsa] means yellow dust, while 미세먼지 [misemeonji] means fine particulate matter. They are related air-quality topics but are not interchangeable terms, and fine particulate pollution does not have a single source.
Service members in uniform

You may see uniformed service members at stations or in public places. South Korea has compulsory military service for male citizens, subject to the applicable rules, classifications, and exemptions. Not everyone serves in the army specifically.
Seeing someone in uniform does not in itself indicate an emergency. Service members may be traveling, commuting, or on leave.
Food in PC cafés

A Korean PC café, or PC방 [pisibang], is a place where customers pay to use computers, often for gaming. Many also sell meals, snacks, and drinks that can be ordered from the computer and brought to the seat.
Menus and prices vary. A meal can cost more than a short gaming session, but there is no fixed relationship between the food bill and the computer-use charge.
Convenient public transportation

Seoul and other major cities have extensive public transport networks. The Seoul metropolitan railway network reaches many surrounding areas, but it does not connect every city in South Korea.
Fares depend on the service and, in many cases, the distance traveled. Seoul subway fares are not a flat one-dollar price for any journey. Check the current fare and transfer rules, and tap your transport card when boarding and leaving as required.
Some large stations also contain shops and restaurants. Gangnam Station is one example with an underground shopping area.
Unattended belongings in cafés

You may notice café customers leaving a laptop or phone at their table during a short absence. This can surprise visitors accustomed to different habits.
It is an observation, not a guarantee that unattended belongings are safe. Theft can occur, so keep valuables with you or ask someone you trust to watch them.
Food delivery to parks and other locations

Food delivery is common in Korean cities, and some parks have designated places to collect orders. The available restaurants, delivery area, fees, and collection instructions depend on the service and location.
Give a clear address or the required pickup-point details; a vague description such as “near a tree” may not be enough. Some grocery services offer early-morning delivery, but availability and arrival times vary.
Crossing busy roads

Take care when crossing roads, particularly at intersections where vehicles may turn across a crossing. Use designated crossings, follow pedestrian signals, and check that approaching vehicles have stopped.
South Korea does have pedestrian-protection rules. The behavior of an individual driver should not be treated as a description of what the law permits.
Conclusion
These are ten unusual things in Korea. How many of them have you experienced or heard about? What kind of things do you want to experience in Korea? Whenever you come to Korea, and whatever you do, I hope you will experience only pleasant surprises!
Check out our list of Basic Korean Phrases for Travelers and Beginners that can come in handy.