Rust 1.98.0
88d9e12ae

# Associated Types

There is a new edition of the book and this is an old link.

> Associated types are a way of associating a type placeholder with a trait such that the trait method definitions can use these placeholder types in their signatures.

    pub trait Iterator {
        type Item;
        fn next(&mut self) -> Option<Self::Item>;
    }

You can find the latest version of this information here.