I've been invited to a Korean wedding for the first time?

Korean weddings are quite different from Western ones and much faster paced. The ceremony itself is usually only about 30 minutes, and the whole event including the buffet takes maybe 2 hours. For dress code, smart casual is perfectly fine. Most guests wear neat everyday clothes rather than formal attire. Avoid wearing white since that is for the bride, and very casual clothes like jeans are frowned upon, but you do not need a suit or fancy dress.

The most important part is the cash gift called 축의금 (chugeuigeum). You put cash in a white envelope and write your name on it. The standard amount for a friend or coworker is 50,000 won, and for a close friend it is usually 100,000 won. Always use clean, unwrinkled bills and odd amounts like 50,000 or 30,000 won are preferred over even numbers. When you arrive, you go to the reception desk first to hand in your envelope and sign the guest book. After the ceremony you head to the buffet or meal hall which is usually on a different floor. Do not feel bad about leaving after eating because that is completely normal at Korean weddings.