When its comes about optimize your site for SERP, I found XML sitemap as an important member of the Seo family . It really helps to make understand and crawl your webpages easily for the search engines.
As we know Sitemaps are URL inclusion protocols as they refer search engines on what to be indexed or not.
How it helps :

• It Lists all URLs from your Website including pages, that would not have been visible by search engines.
• You can command XML sitemap saying the most important to focus on priority pages.
• You can access Googlebot activity through it.