Civilisation is a body of knowledge that has to be kept alive in people, books and machines. If the internet disappeared, three things would decide how fast it could be rebuilt: what was saved, whether it can still be read, and whether anyone knows how to use it.

What to save

Start with what keeps people alive, then what rebuilds tools:

1. Health and first aid: WikiMed, Hesperian guides.
2. Water, food, shelter, energy: Appropedia, practical Stack Exchange archives, the guides on this site.
3. Mathematics and science: open textbooks (OpenStax, LibreTexts), Wikipedia's science pages, simulations.
4. Engineering and repair: electronics, mechanics, materials, iFixit.
5. Computing: an operating system with its source code and compilers (Debian), language documentation, computer science references.
6. Aerospace and Earth: aeronautics and space references, maps, geology.
7. Maps of your region.

Everything above is listed with its newest release on the Downloads page.

How to keep it

• Two copies, two places, two kinds of media. A drive at home, one with someone you trust.
• Check the files with the published SHA-256 sums when you copy them and once a year.
• Refresh every month if you can; at least once a year. Drives fail: spinning disks often last 5 to 10 years, flash drives left unpowered may lose data in a few years, optical discs can last decades if stored well.
• Keep the reader too. Store the Kiwix application for every operating system you may use next to the archives.
• Print what you cannot lose: medicine, water, food and the instructions to rebuild basic tools. Paper has no battery.

How to teach it

Written knowledge is not enough. Learn a craft with a person who has it, write down what you learn, and teach it to someone younger. Schools, libraries and workshops that keep working are the real archive.

Reading

• The Knowledge: How to Rebuild Our World from Scratch, Lewis Dartnell.
• Where There Is No Doctor, Hesperian.
• OpenStax textbooks in your field.