Importance of having a sitemap

Google search engine uses robot to scour the web for pages to add to their index. These robots (known also as web crawlers or spiders) will usually discover your pages by following the links within your site and the links from other web sites.

Having a sitemap makes the crawler's job easier. How?

In cases where your web pages are nested too deep, the crawlers might fail to get to them. That's why having a sitemap is helpful because it allows crawlers to pick up on all of the URLs listed in the sitemap, therefore increasing the chance of getting all of your pages indexed.

Even though you have implemented a sitemap, it does not guarantee that your web pages will be included in the search engine's index. It will only help the web crawlers so that they don’t miss any pages when crawling your web site.