Refers to the number of pages the search engine bots can crawl on a website. A website can be made up of hundreds, thousands, or even millions of pages. It is very important to correctly determine the hierarchy of these pages. A properly constructed page hierarchy helps search engine bots to easily access, crawl, and index all the pages in this hierarchical structure. It is safe to say that the websites that have proper page hierarchy perform quite successfully in terms of crawl depth.