[mattstir]

This is a nice article! I think it introduces some concepts that Rust beginners might question ("what is `Copy` and what implements that?", "what's interior mutability? Doesn't that break the aliasing XOR mutability idea?"), but it gets the practical usage info across.

> Every heap allocation has exactly one owner...

This goes one step further, in that every value including on the stack has a single owner. That's why you can't pass the same `let a = [0; 10];` by value multiple times, even though that's an array on the stack.

> Zero overhead — no extra indirection

I think this is slightly misleading for borrowing, since a reference (`&`) is fundamentally a pointer that the compiler ensures upholds some special properties. So borrows come with a pointer deref when used, similarly to a `Box` or `Rc`, etc. I think the intention is to point out the heap allocations when using smart pointers which are definitely more expensive than `&`, but that doesn't really come across.

Only other call-out is that I'm not sure what the various colours indicate throughout. They look really pretty, but I'm not sure when something becomes teal vs yellow vs orange vs purple.