# Rust 2015

Rust 2015 has a theme of "stability". It commenced with the release of 1.0,
and is the "default edition". The edition system was conceived in late 2017,
but Rust 1.0 was released in May of 2015. As such, 2015 is the edition
that you get when you don't specify any particular edition, for backwards
compatibility reasons.

"Stability" is the theme of Rust 2015 because 1.0 marked a huge change in
Rust development. Previous to Rust 1.0, Rust was changing on a daily basis.
This made it very difficult to write large software in Rust, and made it
difficult to learn. With the release of Rust 1.0 and Rust 2015, we committed
to backwards compatibility, ensuring a solid foundation for people to build
projects on top of.

Since it's the default edition, there's no way to port your code to Rust
2015; it just *is*. You'll be transitioning *away* from 2015, but never
really *to* 2015. As such, there's not much else to say about it!