Wonder how URLS are crawled by Google? It's through a submission service that you have to qualify for as a webmaster. This is how the websites get indexed and ranked so quickly once they publish new pieces or blog articles. Every time you have something new on your website , like content or a new page, you should ping the URL that it's contained in.
Website URL submission is a professional service has been shown to improve indexing within the search engines and this service offers a GUARANTEED crawl of your website by Google, Bing and Yahoo.