Minecraft wiki entry for Things_not_to_do, associated text: The purpose of a shelter is to protect the player from the outside world. Leaving any sort of opening in that shelter defeats the purpose of having one, as monsters can walk right in and attack the player. The player should make sure that their house or fort is secure from all monster attacks, and only has entrances that can be defended easily. If the player wishes to see what is going on outside of their shelter while standing within, windows made out of glass or glass panes are always better than just punching a hole in the wall as an uncovered hole allows skeleton and pillager arrows to strike the player from outside of the house, and allow mobs to path find to the player.