Everything I've written.

A closure is like a sealed box holding instructions plus the values it captured.

This is about the borrow checker that allows many readers or one change permit, never both, and it's enforced by the compiler reading the whole script before the program ever runs.

What a syscall is and why the kernel sits between your program and the hardware. Also why I/O does not mean slow, and why the real waiting happens inside the accept loop rather than in code you write.

Why "cannot infer type parameter" happens when a generic is built but never used, how to resolve it, and how to read what a generic function actually demands.

Why `.route(...).route(...)` chains work. A method taking `self` by value consumes the receiver and hands it back, and the three receiver forms decide what move semantics protect you from.

Why Rust has no exceptions. `Result<T, E>` makes failure an ordinary value the caller must handle, and four tools (`match`, `?`, `unwrap`, `expect`) answer it.

Why calling an `async fn` in Rust runs no code, and how the compiler turns the function body into a resumable state machine whose await points become enum states.