A sitemap can be said to be a protocol that enables a website owner, or operator inform or notify Google and other search engines that they have pages on the website that are available for crawling.
Sitemaps act as the map that leads search engines to your website pages.
Ordinarily, while indexing, it is very much possible for Google to miss these web pages of yours and that would significantly affect your SEO chances.
Sitemaps inform and remind the search engines that you have web pages that are available to be crawled and indexed.
Generating sitemaps is pretty much easy process.
In fact, it is so simple that there are many websites that could help you do it, an example is https://www.xml-sitemaps.com/
After visiting the page, you would be asked to follow four easy steps on your way to generating your own XML sitemap.
There are also tools that help you easily make a sitemap to your Wordpress website. An example of this is YOAST SEO.
The file called robots.txt is another important file in some circumstances. It helps you preventing Google from indexing some parts on your site that should not be indexed (example /wp-admin/ ). This can be done also applying the noindex property to any page.
Why Is It important?
Internal linking can be very effective as long as SEO is concerned, but in cases where your internal linking skill is not perfect, sitemaps can come in. Now, imagine using both of them together.
What a sitemap does for a website is to show Google and other search engines your most important pages. This will increase your chances of being indexed by Google which will, in turn, increase your SEO ranking and help draw in more traffic to your website, and once more traffic starts coming in, we all know what that means – more revenue.
When used optimally with internal linking, it enables Google’s crawler bot (Googlebot) to find your web pages much faster and easier and is more likely to be suggested to users who seek information your website has.
Once the sitemap is created, it's suggested to submit your sitemap to Google and Bing
By the upload of the sitemap to Google (in your Search Console account) you're making life easier for the search engine, as it has a good index to follow and ultimately that's good for you.
In order to use sitemaps to their maximum potential, it is important for website owners to put their best and most important web pages on the sitemap. This is because first impression matters and users are more likely to visit other web pages of yours if they liked what they initially saw.
Did you know? Google suggests that sitemaps are more beneficial to really large websites, websites with large archives, new websites with just a few external links to it, and websites which use rich media content
Expert’s suggestion: “Generating a sitemap is easy when you have the right tools, such as auditing software with a built-in XML sitemap generator or popular plugins like Google XML sitemaps.” – Aleh Baryseich (https://www.searchenginejournal.com/xml-sitemap-best-practices/237649/)