I was using paint.net (An image program) and I decided to open a .pdn file as raw text because I was curious, what I saw was a bunch of gibberish! Why is the data stored like this?
It is most likely stored as binary. This wont make sense to view as a human. However this makes it quick and easy for the program to understand. It also most likely reduces the amount of space the file takes up. Most programs store data like this.