In most cases, once you have your site set up and are happy with the look and feel you will have also likely have set your permalinks found under the WordPress Settings menu item; and, forgotten all about them.

Something to keep in mind when you use WooCommerce is that it has its own custom permalinks; and, if you start with a default installation WooCommerce will add its required pages into the main menu at its top level. If you decide afterwards that you want those pages (especially the “Shop” page) under another page, don’t forget to check under Settings > Permalinks to make sure your WooCommerce custom permalinks are still accurate … in most cases, especially if you are not using the “Default” option, you can just click the “Save Changes” button and everything will sort itself out.