Param is a single URL parameter, consisting of a key and a value.
Params is a Param-slice, as returned by the router. The slice is ordered, the first URL parameter is also the first slice value. It is therefore safe to read values by the index.
Router is container which can be used to dispatch requests to different handler functions via configurable routes
Handle is a function that can be registered to a route to handle HTTP requests. It has a third parameter for the values of wildcards (variables).