Our book, *The Algebra of Data: The Foundation of the Data Economy (*substantially revised edition*)*, has two clear purposes: to explain data algebra in a way that makes it as accessible as possible, and to make serious readers familiar enough with data algebra to actually *use *it.

Still, we expect some casual readers to download *The Algebra of Data* entirely out of curiosity – to see what data algebra is. For them (you?), we split the book between chapters that delve into the mathematics and others that just talk about it. If you’re a less intense reader,