In a nutshell, the URLs are created when you create a page and if the creator takes no special action they are assigned a name based on the Title of the page. Either at creation time or later you can change the URL by editing the page BUT one must be very careful because there may be links to it under the current URL and you will break all of those links.
All pages have a content type the simplest being Page which has little more than a Title and a Body. The Hike content type has a lot more fields. When you create a page with some content type the first component of the path is the content type, thus the URLs of all the hike pages begin /hike/…. And plain pages begin /content/…, etc.
One needs to take care when creating pages for a new content type to select the appropriate page type. For example,