You may be wondering, "How often does Google update its search engine?" Google works in mysterious ways. How does it pick what pages reach the top of its ranking system? How does it separate spam pages from good content? And most importantly, what is a Google anyway? Alright, maybe that doesn't matter, but here's what does: how often does Google update is search engine results?
First, it's important to make a distinction between Google's internal page rank and the one we actually see. Google's mathematical formula, you see, results in fractions. Google page results, obviously, must be expressed in whole numbers. A marginal gain in your page rank score means a change in your position the next time Google crawls.
Google has no "official" policy on when it updates its search results. It neither has a set amount of time when it updates its results, nor does it update in real time. They deliberately keep their policies murky to avoid exploitation of their ranking system, but a few rules of thumb have emerged from the accumulated experience of webmasters. One such rule is that popular sites are "crawled" more often, meaning more frequent updates. Obscure sites can take up to three months before getting an update; not very encouraging for aspiring webmasters. Another factor which effects how often Google updates its search engine is the number of inbound links. Due to the nature of its webcrawler (and webcrawlers in general) Google investigates links it finds on pages it's cataloging. This is one way it judges the quality of webpages, and a fast way to get your website reviewed by its software.
There is no way easy to predict how long it will take Google to update its search rankings, but their webcrawlers are always on the job. Optimize as best you can and be patient, and you'll be at the top of the heap in no time.