Why do people knock at the door three times?

Knocking on the door represents temptation, indicating that the knocker is a stranger; Knocking twice means waiting for the other party to reply, indicating that the knocker knows himself; Knock three times to ask, to say "hello?" ?

Knocking on the door is a sign of respecting the privacy and space of others. As an adult, we should start with "I" and set an example. Let children learn Chinese etiquette imperceptibly in daily life.

Knock at the door with a moderate loudness. If it's too light, others can't hear it. If the noise is too loud, others will resent it. When knocking at the door, don't punch, kick or bang. If there are old people in the room, they will be frightened.

If someone else's door is unlocked, you should also knock at the door first and get the owner's permission before you can enter. When you enter someone's office, you should also knock on the door, indicating a kind of inquiry "May I come in" or a kind of notice "I am coming in".