At a Korean wedding, avoid white, hand a white envelope with cash to the reception desk, and take your meal ticket to the buffet. A guest (하객, hakgaek) is anyone invited to attend the ceremony.

What to Wear: Avoid White
Do not wear white, ivory, or cream. Choose a neat suit or dress instead. White is considered the bride's color, and wearing it to an event where she should stand out breaks etiquette.
The dress code is semi-formal. For men, a navy, charcoal, or black suit with a simple tie is a safe choice, and a suit without a tie is also fine. For women, a dress or blouse in navy, burgundy, or a pastel shade works well.
Black is accepted as a formal color, but some people advise women against it. If you are a foreign woman attending for the first time, choose navy or burgundy instead of black.

Gift Money: ₩50,000 to ₩200,000 by Relationship
Gift money (축의금, chugigeum) is cash you give to congratulate the couple. The closer you are to the bride or groom, the more you give. The amount is a social custom, not a legal rule.
- Distant acquaintance: ₩30,000–₩50,000
- Coworker or casual friend: ₩50,000
- Close friend: ₩100,000
- Boss: ₩100,000–₩200,000
- Family or very close relationship: ₩100,000–₩200,000 or more
The range for family and very close relationships is wide, so choose within it based on how close you are.

Write Your Name on the Back of a White Envelope
Put the money in a white envelope and write your name on the back. Use clean, new bills with no creases. For ₩100,000, two ₩50,000 notes is the standard.
Do not use a black envelope. Those are for funerals. At weddings, cash is the default rather than a physical gift. Give a physical gift only separately, to a close friend.

Arrive 20–30 Minutes Early and Go to the Reception Desk
Arrive 20–30 minutes before the ceremony starts and go to the reception desk first. This is where guests hand in their gift money envelopes. There are separate desks for the groom's side and the bride's side. Use the one for the person who invited you.
When you hand in the envelope, you receive a meal ticket (식권, sikgwon). It is your pass for the buffet, so keep it in your wallet.

The Ceremony Lasts 20–30 Minutes, Followed by a Buffet
The ceremony itself lasts about 20–30 minutes, and the meal is a buffet. The buffet opens at the same time as the ceremony, so you can eat before, during, or after it. The buffet is a place to eat, and also a place for guests to talk and offer congratulations.
A group photo session follows right after the ceremony. If you want to join the photos, stay about 15 minutes longer. A full visit takes about 45 minutes to 1 hour. In the bride's waiting room, you can take a photo with the bride.

If You Can't Attend, Send ₩30,000–₩50,000
Guests who cannot attend usually send ₩30,000–₩50,000 by bank transfer. Many people use KakaoPay for the transfer.

In short, Korean wedding guest etiquette comes down to three things: neat clothes without white, a white envelope with an amount that fits your relationship, and arriving at the reception desk 20–30 minutes before the ceremony. With these three in place, even a foreign guest at their first Korean wedding can offer congratulations without feeling out of place.