HANGUL
The official writing system for South Korea is Hangul (한글), which is the name for the Korean Alphabet system. That means you can say Hangul and Korean alphabet interchangeably since they mean the same thing. Korean is the official language of South Korea, and it uses Hangul as its alphabet and writing system.
It is spoken by almost everyone in the Republic of Korea (South Korea) and the Democratic People's Republic of Korea (North Korea). It is also spoken by around 1.9 million people in China, mostly in the North-East of the country.