We query each search engine to see how many pages of your site it reports in its index.
You can also see how many pages our search engine robot has found.
This is a useful quick check to ensure that your website is listed in the page search engine indices.
You can also use this graph as a reference point to ensure that everything is ticking over nicely. If there is a sudden change in the number of pages indexed then perhaps something untoward has occurred, or more likely the search engine in question is temporarily not reporting correctly.
Over time as you add more pages to your site you should expect the corresponding volume of pages in each search engine to grow accordingly.
If the number of indexed pages does not reflect the volume on your site then perhaps the search engines have an issue with some reaching some parts of your site.
You should seek some professional SEO help.