The concept of folk characters in ancient Chinese writing was first introduced in Shuo Wen. These characters were not highly valued due to the focus on standard forms. However, studying these folk characters can help us understand how Chinese characters have evolved over time, including their simplification. The types of folk characters in Shuo Wen show characteristics like reflecting the time and place they were used, being popular and simple, and having phonetic qualities. By paying more attention to these characters, we can learn about the evolution of Chinese writing shapes and simplification rules.