How long can you live in South Korea without citizenship?

Excuse me, I'm considering relocating to South Korea for work purposes, but I'm not a citizen. I was wondering, how long can someone live in South Korea without citizenship? I've heard about visas and permits, but the information is quite overwhelming. Could you please clarify the process and the duration of stay for non-citizens? Also, are there any specific requirements or conditions that need to be met to extend a visa or apply for permanent residency? Thank you for your time and assistance.