Chapter 1 Introduction Welcome to “The Rust Programming Language,” an introductory book about Rust. Rust is a programming language that’s focused on safety, speed, and concurrency. Its design lets you create programs that have the performance and control of a low-level language, but with the pow- erful abstractions of a high-level language. These properties make Rust suitable for programmers who have experience in languages like C and are looking for a safer alternative, as well as those from languages like Python who are looking for ways to write code that performs better without sacrificing expressiveness. Rust performs the majority of its safety checks and memory man- agement decisions at compile time, so that your program’s runtime performance isn’t impacted. This makes it useful in a number of use cases that other languages aren’t good at: programs with predictable space and time requirements, embedding in other languages, and writ- ing low-level code, like device drivers and operating systems. It’s also great for web applications: it powers the Rust package registry site, crates.io! We’re excited to see what you create with Rust. This book is written for a reader who already knows how to program in at least one programming language. After reading this book, you should be comfortable writing Rust programs. We’ll be learning Rust through small, focused examples that build on each other to demon- strate how to use various features of Rust as well as how they work behind the scenes.