I just moved to Korea and I'm overwhelmed by grocery shopping here?

Totally understand the overwhelm! Here is what helped me figure it out. The major chains are Emart (이마트), Homeplus (홈플러스), Lotte Mart (롯데마트), and Costco. Emart is the biggest and has the widest selection with good house-brand products called No Brand which are budget-friendly and surprisingly good quality. Homeplus is similar and often has slightly better deals on imported products. Lotte Mart tends to be in more central city locations.

For daily shopping, most neighborhoods have traditional markets called 시장 where you can get incredibly fresh produce, meat, and fish at lower prices than supermarkets. The vendors might not speak English but pointing and using Papago works perfectly fine. Small convenience-style supermarkets like GS The Fresh and Emart Everyday are great for quick runs. Online grocery shopping through Coupang Rocket Fresh or Market Kurly delivers fresh groceries to your door, often by the next morning if you order the night before. One important tip is that many supermarkets are closed on the second and fourth Sundays of each month by law, so check before you go. Each chain picks different rest days, so if one is closed, another nearby might be open.