Possible Duplicate:
What's the shebang/hashbang (#!) in Facebook and new Twitter URLs for?
I noticed that some popular sites started switching to a new URL (convention?), in which a URI segment is no longer prefixed by / but rather by #!/.
For example, if you type into Twitter http://twitter.com/stackoverflow, it will immediately redirect to http://twitter.com/#!/stackoverflow.
Had I seen this on Twitter only, I wouldn't have thought twice about this, but now I am seeing this in other sites.
Is this a new convention for URL redirection? Where can I learn more about this?
It was started by Google ( http://code.google.com/web/ajaxcrawling/ )
If you're running an AJAX application with content that you'd like to appear in search results, we have a new process that, when implemented, can help Google (and potentially other search engines) crawl and index your content. Historically, AJAX applications have been difficult for search engines to process because AJAX content is produced dynamically by the browser and thus not visible to crawlers. While there are existing methods for dealing with this problem, they involve regular manual maintenance to keep the content up-to-date.
Look at this answer here:
What's the shebang/hashbang (#!) in Facebook and new Twitter URLs for?
The opinion on using this is split - Gawker had major issues after taking this up : http://www.webmonkey.com/2011/02/gawker-learns-the-hard-way-why-hash-bang-urls-are-evil/