Any trail which is created by the site’s routing feature can now be saved as either a private or public trail. Public trails show up as black GPX icons on the map and are visible for all visitors, private trails show up as red GPX icons and are only visible to the user who saved the trail.
In order to be able to save a trail, you need to sign in.
Additionally, you can bookmark or pass the URL/address of a saved public trail to someone else: In a saved trail’s info sheet, click on [Open in a new window] and then copy&paste the URL/address you get.