Nearly 3 million of them.
The Internet Archive Manual Library is a collection of manuals, instructions, walkthroughs and datasheets for a massive spectrum of items. Manuals covering electronic and mechanical products, instructions on mixing or blending items, and instruction sets for software and computer items are all included.
Having the manual for an item can mean the difference between that item being useful (and therefore not immediately junked) and being forgotten, or replaced with similar products. They also give insight into the intentions and goals of the companies making these products, as well as avenues of troubleshooting and repair.