The two ideas that make Rust different from every other systems language: a value has exactly one owner and is freed deterministically on scope exit, and errors are values on the type-checked return path rather than exceptions. This module covers moves, Copy and Clone, shared and exclusive references, enums, Option, pattern matching, panics, and Result with the question mark operator.

The three abstractions that let Rust stay allocation-free while looking high-level: generics (monomorphized at compile time), traits (shared behavior and dynamic dispatch), and lifetimes (proving references never dangle). The module closes with modules, closures, and the iterator combinators (map, filter, collect) that make data pipelines idiomatic.

Apply everything from Weeks 1 through 3 to build a single end-to-end Rust command-line program. The capstone has two tracks: a local project that ships with tests and a clippy-clean build, and a zero- install playground reading that works in any browser via the Rust Playground at play.rust-lang.org.