• Specifying that types must implement certain traits. see: Bounds
• Multiple trait bounds
• Using the where clause for complex trait bounds.
• Empty Bounds Note: Trait Marker can also be used as Either Or Trait Bound
• Unit Clarifications with Phantom Type Parameter ( std::marker::PhantomData )

<aside> 💡 A phantom type parameter is one that doesn't show up at runtime, but is checked statically (and only) at compile time.

</aside>