Names and characters are generally chosen by elders. In ancient times, men were given a given name when they were 20 years old, and women were given a given name when they got married. When a person reaches adulthood, he is already an adult and needs to be respected by society. It would be disrespectful for peers to only call him by his first name, so he needs to choose a word for himself and use it when interacting with others in society to show mutual respect. Therefore, when the ancients reached adulthood, their names were only used by their elders and themselves. Calling themselves by their own names showed humility, while the characters were used to be addressed by people in society.
There are two types of titles: self-chosen ones (called self-titles) and those given by others (called honorific titles, elegant titles, etc.). I started it myself to express a certain intention.
/q/1364941363067240 There is a very detailed explanation here.
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