system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are compressed and uncompressed files, how does it all work and why compressed files take less storage?
gpt
File compression saves hard drive space by removing redundant data.

For example take a 500 page book and scan through it to find the 3 most commonly used words.

Then replace those words with place holders so 'the' becomes $, etc

Put an index at the front of the book that translates those symbols to words.

Now the book contains exactly the same information as before, but now it's a couple dozen pages shorter. This is the basics of how file compression works. You find duplicate data in a file and replace it with pointers.

The upside is reduced space usage, the downside is your processor has to work harder to *inflate* the file when it's needed.