Is it absolutely necessary to remove numeric parameters from a url such as: www.site.com/keyword/category213.html to ensure the page is indexed and if so, why?
The URL you provided doesn’t contain any parameters. It’s a flat HTML file so search engines shouldn’t have any problems indexing it.
It’s URLs that contain “query strings” that generally contain parameters or variables. For example:
The question mark indicates the page is dynamic and therefore requires some type of server computation to display. The page URL above contains only one parameter (productid).
See more about how Google defines dynamic vs static URLs.
These days, most search engines can index pages that contain a single parameter. It is generally when multiple parameters are used in page URLs that search engine indexing problems occur.
As Google says in their Design and Content Guidelines:
“If you decide to use dynamic pages (i.e., the URL contains a “?” character), be aware that not every search engine spider crawls dynamic pages as well as static pages. It helps to keep the parameters short and the number of them few”.
Multiple parameters are often needed for large sites with multiple page templates and dynamically generated content for each section of each page. Multiple parameters are separated via an ampersand (&), for example:
The URL above is instructing the template for the page product.asp to query the database and load the page content for product id number 2 AND specifically the data for the large version of this product whenever anyone accesses this web page.
This type of URL is more difficult for a search engine to index because they can’t identify what the multiple parameters mean or whether the URL is a unique page.
So in this case the webmaster has the option to re-write the URLs at the server level to remove the parameters or else block search robots from indexing URLs containing multiple parameters.
But if you’re in doubt, I wouldn’t worry too much about your dynamic URLs. Google and the other search engines are pretty good at parsing and determining what parameters to ignore.