Any regular semi-technical user of your site should be able to navigate 90% of your app based off memory of the URL structure. In order to achieve this, your URLs will need to be pragmatic. Almost like they were a math equation—many simple rules combined in a strategic fashion to get to the page they want.

The most valuable aspect of any URL is what lies at the top level section. Think about how big of a deal Facebook’s rollout of usernames was. Available URLs are a lot like real estate and the top level section is the best property out there.

Kyle Neath.