http://chimera.labs.oreilly.com/books/1234000001802/index.ht...
Mastering bitcoin is the most recommended book on the topic and it's (mostly) open source.
For a high-level introduction, this article in The Economist is where I'd advise someone to start: http://www.economist.com/bitcoinexplained
Then, to make things feel more grounded, watch this video of a maths teacher walking you through the mechanics of what actually happens. He starts with "four friends who sometimes spot each other $5 for lunch" and then builds from there with great visuals, so it is quite accessible. https://www.youtube.com/watch?v=bBC-nXj3Ng4
This covers bitcoin from total beginner to expert level (technology, mining, trading...): http://lopp.net/bitcoin.html
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&c...
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&c...