An XML sitemap is a big list of all of the pages on your website that you want search engines to find and show in their search results. It’s only designed for search engines (not real people like you and me) so that they can easily crawl all of your pages.
What does validating a sitemap mean?
Due to XML sitemaps being automatically generated and only really designed for search engines, there is a set of protocols that each one needs to adhere to. This means that when search engines come along and take a look at it, they can process it easily and correctly.
Sometimes, weird little errors can creep into sitemaps which stop a sitemap from being valid. If this happens, then search engines may struggle to process your sitemap correctly and lead to them ignoring it. Being ignored is a little rude, but we don’t blame them. The search engines only want to spend their time on good stuff and an invalid sitemap isn’t good.
Why is validating a sitemap important?
Search engines need to crawl the pages on your website which can then lead to them indexing them. Without this happening, pages can’t rank in organic search results.
Having a sitemap in place can help them with this process. Now, a sitemap on it’s own won’t fix crawling issues that you have on your website such as bad navigation or poor internal linking. But it can help just to nudge search engines in the right direction.
Not to mention that you can get additional, useful reports from places like Google Search Console by having a sitemap live and crawlable.
That’s a long way of saying that validating a sitemap is important because if it’s not valid, then it may be ignored altogether.
Is an invalid sitemap a big deal?
Honestly, there are worse problems to have as an SEO. But having a valid sitemap in place is one of the most basic things that you can do to help with correct crawling and indexing of your pages. So you might as well get it right because the effort is very, very low.