# 查看 Rust Crates 的 Features

## 背景

Tokio has a lot of functionality (TCP, UDP, Unix sockets, timers, sync utilities, multiple scheduler types, etc). Not all applications need all functionality. When attempting to optimize compile time or the end application footprint, the application can decide to opt into only the features it uses.

## 声明可选的 Features

You are encouraged to document which features are available in your package. This can be done by adding doc comments at the top of lib.rs.