Definition: A URL (Uniform Resource Locator) is a web address that tells a user's computer (the client) where to find a website on the internet. The most important aspect of URLs in ecommerce is optimization, which significantly impacts search engine performance.
URLs are a specific type of Uniform Resource Identifier (URI). While most commonly used to find a specific web page (or a specific version of a web page, in the case of archives that have multiple copies), URLs can also be used to navigate a page (by going to particular sections, as through a table of contents) or tell a site to execute a specific type of action (such as highlighting certain words on the page when the user arrives).
The only other type of URI is the Uniform Resource Name, which is used to help identify unique items (specific editions of books, films, etc.). However, as most companies have no need to use URNs, they are not used in ecommerce.
URLs have significant SEO implications, helping search engines contextualize the purpose of a web page. To maximize ranking in search engines, URLs should be optimized according to standard best practices.
In general, URLs should:
Be clearly readable by humans, ideally acting as a short description of the content appearing on the page.
Match the title of the page as closely as possible. If it needs to be forced, some variation is fine.
Avoid the use of parameters, especially if the page might display in search engine results.
Minimize the use of numbers and unfamiliar characters, since letter-only URLs are easier to type and remember.
Use hyphensto denote separate words - search engines do not always interpret underscores to meant the same thing.
Avoid repeating keywords within the URL itself, since that's not necessary for SEO purposes and might make the URL harder to read.
When sharing a link, use a URL shortener so the link is short and sweet.
Note: These rules apply mainly to URLs that might display in search engines or might be looked at by humans. It's possible to break some of these rules when URLs aren't as visible - for example, parameters can be used when linking off-site or generating unique on-site pages.