Citizens of certain countries can visit Korea without a visa for a limited period of time. Generally, citizens of most countries are allowed to stay in Korea for up to 90 days without a visa. However, some countries have different agreements in place with Korea that allow for longer or shorter stays. It is important to note that even if you are allowed to stay in Korea without a visa, you may still need to meet certain requirements before entering the country. If you wish to stay in Korea for longer than the permitted time without a visa, you will need to apply for an extension or obtain a visa.