Ownership

The single-owner mental model, moves versus copies, the borrowing rules, and lifetimes as the compile-time bookkeeping that answers "how long does this reference stay valid."

The single-owner rule, moves, and `Drop`.

Moves vs. copies, `Copy`/`Clone`, and ownership transfer.

Shared `&` vs. mutable `&mut` and the aliasing rules.

How it reasons, common errors, and how to satisfy it.

What lifetimes are and why references need them.

Writing `'a` bounds in functions, structs, and impls.

The rules that let you omit most annotations.

Designing APIs that borrow well and clone rarely.