A trait is a set of methods a type promises to provide. It is not a base class: there is no inheritance, no shared fields, and no constructor.

trait Health {
    fn name(&self) -> String;

    fn status(&self) -> String {
        format!("{}: ok", self.name())
    }
}

name is required. status has a default implementation, written in terms of the required methods — an implementor gets it for free and may override it.