Comments

Rust comments are similar to C++ except they may contain Unicode because .rs files are UTF-8 encoded:

/*
 This is a comment
*/

// This a comment with Unicode, 你好

But in addition anything that uses triple slash /// annotation can be parsed by a tool called rustdoc to produce documentation:

/// This is a comment that becomes documentation for do_thing below
pub fn do_thing() {}
/// Returned by server if the resource could not be found
pub const NOT_FOUND = 404;

Runnining cargo doc on a project will cause HTML documentation to be produced from annotated comments within the file.

Annotation is written in Markdown format. That means you have a human readable language for writing rich-text documentation and if it's not enough you can resort to HTML via tags.

See here for full documentation