How does photos store and use images?

Hello,

I am curious how Photos stores the images/videos. If I create a new album and put images, videos, bursts etc. does Photos copy the image file to the new album or does it act like a pointer for the image?

If I have the same image, in 3 “private” albums and the same image in 3 “shared” albums is the photo now taking up 6 times the storage because it is located in 6 different albums, or are all the albums just “pointing” back to the one image file saving a bunch of space?

I guess simply, if I add a single image to multiple albums am I losing storage each time I add the image to a different album?

Thanks for the help!