It's unfortunately split up into two parts due to requirements on the blog that published it (literally "Founder Scene"), but this hits on some of the basics of

It's unfortunately split up into two parts due to requirements on the blog that published it (literally "Founder Scene"), but this hits on some of the basics of collaborative filtering. The next part gets into item-based collaborative filtering and a little on graph-based stuff. I'll post the second part here when it comes around. The article is definitely targeted at being a quick introduction to how recommendations work rather than being a how-to. Most Gründerszene's subscribers aren't developers so it's an attempt to present the stuff in a digestible format.