Google’s John Mueller was asked how someone can help Google understand which pages of a site it really wants Google to index. A webmaster said that Google was only indexing 10% or so of the site’s pages in the sitemap file. He asked how can they notate which pages are more important if Google doesn’t look at the priority field in XML Sitemaps.
John said it is true that Google doesn’t really look at the XML sitemap priority field. So instead, you really need to communicate which pages are more important to you through your internal linking. The more you link from your more important pages to other pages, the more Google will understand that the pages you are linking to on your website are important.
Often that means which pages have links from the home page of your website. If you link to 10% of your pages from your home page, Google will likely think those 10% of those pages that you are linking to from your home page are more important than the other 90% of your pages. Of course, there are always exceptions but that is the general rule.
John said at the 5:55 mark into the video:
To give a sense of importance within your website you’d need to do that more with regards to internal linking. So less less with just purely the sitemap and more kind of making it easy for Google to recognize when we crawl your site which of the pages you care about. The most usually that’s like we would start with your homepage, depending on the website but in many cases we start with the homepage and things that are linked from the home page we would see as being more important than things which are just like i don’t know five or six steps distance from the home page.
Here is the video embed where the question starts:
Forum discussion at YouTube Community.