system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What exactly is happening during the "Loading" screen on games, programs, machines, etc?

Pretty much the title, and why do some take longer way longer than others?
gpt
Your computer has lots of storage space (like kitchen cabinets), but much less working space (like kitchen counters). You can't just keep all your groceries out on the counter or else you'll run out of room, so you need to put it all away into the cabinets. You can store everything when it's put away, but then you need to take it out and put it on the counter when it's time to use it. 

Your computer doesn't have enough "counter space" to have the entire game ready to go all at once, so it leaves a bunch of it in the cabinets until it's needed. The "loading" is what happens when the computer needs to put some parts back in the cabinet, and bring new parts down to the countertop so they're ready to be used.