Google manually visit your web site then search for the new links and contents and then add the good quality one in to his web as new contents. thanks
Google crawler is an program(code) who read your web page. Crawler go on your web-page as a chief guest, crawler can stay on your web-page for few second or can stay for few minute, it depends. When crawler is on your page at that time he visits on your internal pages step by step, may be not visit. Then crawler take an snap shot of visited page(when you check page cache then this snap shot appears to you including date of crawl). Crawler index that page in the google repository. That's why when we search on google then google provides result including 3 thing- 1)Title 2)Descreption 3)URL also a link for check your web-page cache date. Hope you can understand it easily.
You can get info about google crawling over here.., http://www.google.com/support/webmasters/bin/answer.py?answer=182072
Used this link for Google Crawl a website.http://www.marketing-jive.com/2011/08/3-ways-to-help-google-crawl-your.html
Hello Each and every search engine has its own crawler, the main work of crawler is to find out the new on web, if you make any change in your website or crawler find out your links on the web with some popular website then crawler will crawl your website. Hope you understand
first of all Do all OnPage SEO Steps after that Submit your URL in Google webmaster account and after that Do OffPage SEO Tips.
It a simple matter.......... google crawl your site.Collect different data........ meta description ,tittle and page url.also take snap shot which we see in cache