What is South Korea most popular business?

Could you please elaborate on the topic of "What is South Korea's most popular business?" I'm particularly interested in understanding which industries or sectors are thriving in the country and why they have gained such widespread popularity. Also, are there any specific companies or brands within these businesses that are particularly renowned or successful in South Korea? Could you provide some examples or insights into what makes these businesses so popular? Thank you for your time and assistance in addressing this question.