How is it that questions posted to the Stack Overflow show up as #1 in Google search results just minutes after being submitted? What SEO practices are being used to generate this sort of up-to-the-minute accuracy?
Sites with high PR and are frequently updated will have their sites crawled more quickly then normal. So it's not a technique, per sé, so much as it is a result of the site being popular and constantly changing.
Stack Overflow and other Stack Exchange websites are favored by Google and other search engines because of the following:
- great content architecture and structure,
- a lot of original content,
- many quality inbound/outbound links,
- appropriate on-page keywords/tags,
- an internal rating system,
- dedicated community moderation,
- new content all the time.
Due to this, and the amount of new information appearing on Stack Exchange every moment, Google indexes Stack Overflow at 10 times per second — which means that any changes or new posts are picked up very soon.
It is possible to ping Google when new content is posted. WordPress has this feature built in StackOverflow and other StackExchange sites have likely also implemented it.
WordPress uses http://pingomatic.com/ to automate the process. This article also says that Feedburner can be used for that purpose. These aggregate ping services end up pinging Google and other search engines for you. Of course you could just ping the ones that you care about yourself. Google's ping service is at: http://blogsearch.google.com/ping
I've done a LOT of experimenting with Google rankings. I know I posted a question to one of the Stack Exchange sites and was surprised that the question hit my Google Alerts (http://www.google.com/alerts) withing 24 hours.
Google always ranks Wikipedia and Stack Overflow really highly. I believe there are two reasons for this.
Neither of these two sites "sell" anything. They are informational. Google knows that any Wikipedia page has no hidden agenda. Anyone who visits one of their pages will find what they are looking for, probably more than they are looking for.
Both of these sites are constantly being updated and rely on content created by intelligent users who aren't selling anything. Again, 99% of answers really shed light on a myriad of topics.
I don't think this is PR related because my unrated blog (
PR0), when I post a new article, it does appear in the google search a few minutes after I first submit the new post.
IMO this is because I use a sitemap.xml + webmastertools + ping google about changes in the sitemap.