It let you prioritize your pages and tell google to index certain urls first and others later (priority 0.0 - 1.0). So you show the good quality content first and others later to google.
ever you all using wordpress sitemap plugin? past time i have been using it but i have error sitemap report on google sitemap? can help me?
you are going give a list of your pages to googlebot with a sitemap . because this, sitemap is important for all types of web sites
If you have a large site, you may want xml priority values for all pages calculated based on your website internal linking structure. Check my article about priority values for more details. It will in most cases help getting your websites indexed quicker, but no absolute guarantee though.
As a rule, it is always good to submit a sitemap to Google. It makes it easier for Googlebot to find all of your pages, especially if they have no/few inbound links. I can't think of a reason not to submit a sitemap, unless it is for a tiny site with all pages already indexed.
to submit google sitemap is to give google bot the way to visite your site. Like you go to supermarket and someone ask you to buy milk,you may spend the time to find where is the milk, On the other hand if that one give you a mapwhich show the location of milk shelf, you can fing it in few minut. Remeber google site map is the Map of your site location that will give someinfomation to your bot to find what you want it to find.