In the past, I have pasted apps into TextEdit, which would show something like the following. I always thought that this was a convenient way to store app icons (as .icns files), in case I ever wanted to back a list of my apps up (just the names/icons, not the apps themselves) to manually download and install later.
I recently tried pasting about 20 apps into a TextEdit document, and the document turned out to be about 3GB large. This definitely is much larger than the .icns files for 20 apps. What exactly is stored in this TextEdit document?