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What are 한자(漢字)?
Shortly after you begin studying you may come across the statistic that 70% words used in the Korean language are of Chinese origin. These were originally represented by Chinese characters. This logo graphic writing system was invented thousands of years ago and have continuously developed as more concepts needed to be expressed.
Initially only used by the higher classes due to lack of public education. In the current age it is easy for many in the developed world to spend time on learning the characters due to an abundance of information and resources available via the internet.