A <Route> component in React-Router can be configured to accept URL parameters that change for a given object. For example, to display user information for a given userID, the URL path could look like '/user/1' for a user with a userID of '1', and '/user/123' for a user with a userID of '123'. The last portion of the URL is dynamic; however, in each instance, the rendered component would perform the same operation for a given userID.
An example of such a use case is Twitter's profile page. The page accepts twitterID and displays the feed for the given user.
A <Route> component can be configured to accept the dynamic portion in the URL by appending an additional path in the 'to' prop, prefixed with a colon (:) as seen here: