I received an email from a company providing search engine promotion telling me that my company's website doesn't have a "Google Sitemap File". It also indicates that it's not a regular "site map" for people to visit online but a script called that helps Google to read and index your website overall content. And yes, a file like this would cost $125 if I want to buy from them.
I am not going to bother to spend that much money for such a file like this but it does remind me to review what Google suggested. It's been a few years since last time I checked their recommendations.
Referring to what Google says, Sitemap helps speed up the discovery of your pages and is particularly helpful if the site has dynamic content, pages that aren't easily discovered by following links. However, it also states that sitemaps do not replace Google's normal methods of crawling the web. It's important but there are many other factors that influences the process.
Google also has provided an easy way to help you to submit the sitemap file so it may be the time for you to think about re-submitting your site with your new created/updated sitemap. It's much easier than before.
What is a Sitemap file and why should I have one?
How do I submit a sitemap?