---
title: "Rust's ownership and borrowing in 150 words"
description: "Recently, I wrote on reddit that a Rust book won’t become obsolete in the next years if it focused on explaining concepts instead of current APIs. At basically the same time, I tried to explain some …"
image: https://deterministic.space/rust-ownership-and-borrowing-in-150-words-og.png
url: https://deterministic.space/rust-ownership-and-borrowing-in-150-words.html
author: "Pascal Hertleif"
date: 2016-08-02
categories: ["rust","teaching"]
---

# Rust's ownership and borrowing in 150 words

Recently, I wrote [on reddit](https://www.reddit.com/r/rust/comments/4vfzvc/list_of_rust_books/d5y8i0o?context=3) that a Rust book won't become obsolete in the next years if it focused on explaining concepts instead of current APIs. At basically the same time, I tried to explain some of Rust's concepts to a friend. I think I came up with a quite concise description (maybe even explanation) of "ownership and borrowing" (the concept that differentiates Rust from most other programming language).

- - -

**Ownership**: You own a resource, and when you are done with it, that resource is no longer in scope and gets deallocated.

**References** to a resource depend on the lifetime of that resource (i.e., they are only valid until the resource is deallocated).

**Move semantics** means: Giving an owned resource to a function means _giving it away_. You can no longer access it.

To _not_ move a resource, you instead use **borrowing**: You create a reference to it and move _that_. When you create a reference, you own that reference. Then you move it (and ownership of it) to the function you call. (Nothing new, just both concepts at the same time.)

To manipulate a resource without giving up ownership, you can create one **mutable reference**. During the lifetime of this reference, no other references to the same resource can exist.

That's it. And it's all checked at compile-time.