$routeParams is a service of angularjs that can be used to get the current set of route parameters i.e. URL parameters. ngRoute module is used to work on it.
The route parameters consist of $location’s search() and path(). The path parameters will be extracted when the route path is matches.
When a route change completes, $routeParams are updated. $route.current.params can be used to access the new route's parameters.
In app.js we create an app module and passes the parameters ngRoute and controller name.