Generally, there can be 2 types of URLs used by an online store - dynamic and human-readable URLs.
The first type is the URLs formed dynamically based on a query to the store's database. For example, a typical product page URL may look like the following:
Dynamic URLs containing query strings pose a problem for SEO because they stop many search engines from indexing such pages. They are also difficult to read and remember for your store's human visitors.
Human-readable or "clean" URLs, as they are called in X-Cart, are SEO-friendly URLs that are used instead of dynamic ones. With clean URLs enabled, the above-cited page URL could look like
Your online store uses the human-readable URL format by default. Therefore, you have complete control of what the URL says to your customers. In addition, you can create a clean URL for any page in your store at any time simply by saving/updating the page with the "Autogenerate Clean URL" checkbox enabled.
If, however, you prefer to add or edit a previously added clean URL manually, you can do so by leaving the "Autogenerate Clean URL" option disabled and editing the contents of the "Clean URL" field directly.