/#!/ Why is there an exclamation mark in Twitter URLs?

[petervandijck]

http://twitter.com/#!/petervandijck I understand the hash, but why the exclamation mark? Just ugly implementation detail?

[CPops]

A url hash that starts with an exclamation point is a convention created by Google to allow Ajax web apps to be crawled by search engines.

http://code.google.com/web/ajaxcrawling/docs/specification.h...

[answerly]

It indicates to Google (and presumably other crawlers) that the site supports the AJAX crawling scheme. More here:

http://code.google.com/web/ajaxcrawling/docs/getting-started...

[sushi]

It's called "shebang" and a discussion was done on SO few weeks back.

http://stackoverflow.com/questions/3009380/whats-the-shebang...

Basically the purpose of the shebang in this case is to tell Google how to index pages.