system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What *is* the space that gets taken up when I add "data" to my hard drive, phone, memory card, ect., and how exactly does it work?

I really don't know how to properly explain, but when I add, say, music to my phone, what exactly happens that limits the phones capacity? The phone doesn't gain any weight, and nothing actually goes inside it. There is no physical "empty space" inside of a storage device, correct? What is causing the phone to just "not process" the data? And what does data even look like?
gpt
Think of the storage as being lots and lots of switches.

When your phone is empty, the position of these switches - whether they are on or off - really doesn't matter.

When your phone is full, the switches are all being used to represent the photos, apps and and music in your phone. You can't install more apps, because there are no free switches to move into the right position to represent your new app.

Some of the switches are used simply to keep track of what the other switches are being used for, as well as keeping track of which switches are free for use.