You won't give the key to the door card when you stay in a hotel, will you? How to use the key card? How to lock the door when going out during the day? thank you

Yes, large hotels generally use key cards! A key card is like a bank card to withdraw money. After you plug it in, the door will open, but you have to open it with a card every time you close it! When you go out, you usually close the door! I suggest you try to push the door when you go out to see if it is closed! I used to stay in a hotel, turn on the light, open the door, and use my card for water!