Crawl Depth of a page refers to the number of clicks is needed to reach a particular page on a website, starting from the domain’s homepage using the shortest path as possible.
Easy to reach pages end up being visited by both search engines and users most often, so it’s important to make sure that every page on your site that contains value is easily accessible.
In the following Moz video, Eli shows how to analyze your site’s architecture via crawl depth, so you can adjust your internal linking structure to ease access to your most important pages and save on valuable crawl budget.