It is the means by which you can pass from one room into another, or from one confined area into another confined area.
It is a passage way but one that is not free for all to pass through. You may pass if you have the means to open the door, like opposing thumbs, or a key, or the ability to pick a lock, but if you do not have these skills or tools then access is denied. You are not welcome.
The door may be opened for you if you request it of another who has the skill or tool to open the door but then it is their decision whether they choose to open the door for you. They themselves become the door. The ability to open them, pass through, becomes one of psycholgy. Do they understand you want to pass through the door? Do they like you? Do they think you belong on the other side of the door? They are the door keeper.
But what if this is the door...
Is it an invitation to challenge the etiquette of doors, ignore the rules, go invited around the door?
Is it still a door if it does not contain an area and prevent access from undesirables?
Can it call itself a door if it does not open?
Who is the keeper of this door?
Who has the key to that lock?
I knocked but noone came.
I'll try again tomorrow.
Joining in with The Gallery prompt 'Door' for Sticky Fingers Blog