What's the shebang/hashbang (#!) in Facebook and new Twitter URLs for?

This tells Google how to index the page. code.google.com/web/ajaxcrawling.

I often find that the page loading hangs on a shebang URL on facebook (even after many reloads), but if you manually remove the #! , it works. Not to mention you often get "1.5 URLs" (i.e.

The old URL remains, and just has the new part added to it (i.e. Photo. Php?

Id=... twice, but with different ids). Not to mention that "#!" is also added to facebook-mail URLs, which probably aren't (and shouldn't be) indexable. In any case I find the shebang extremely annoying since it seems to be the reason for so many page faults on my slow home line.

– Pedery Oct 15 '10 at 3:15 8 That Facebook has bugs doesn't make those bugs the fault of two characters in the URL. If the site is coded properly to understand and generate them, crawlable AJAX URLs are quite handy. Lots of other things on Facebook glitch out, too.

– ceejayoz Oct 15 '10 at 3:19 6 @Pedery: I have only ever seen that issue with Facebook. I agree, it drives me up the (non-Facebook) wall all the time. – BoltClock?

Oct 15 '10 at 3:22 3 As for search engines, having an indexable AJAX URL doesn't make the page get indexed anymore than having an indexable non AJAX URL does. Facebook uses this URL format for more than just Google's benefit - it also makes pages accessed via AJAX on Facebook bookmarkable when they otherwise wouldn't be. – ceejayoz Oct 15 '10 at 3:24 6 For some interesting caveats, also read this article: isolani.co.

Uk/blog/javascript/BreakingTheWebWithHashBangs – Michael Stum Oct 15 '107 at 1:22.

The octothorphe/number-sign/hashmark has a special significance in an URL, it normally identifies the name of a section of a document. The precise term is that the text following the hash is the anchor portion of an URL. If you use Wikipedia, you will see that most pages have a table of contents and you can jump to sections within the document with an anchor, such as: https://secure.wikimedia.Org/wikipedia/en/wiki/Alan_Turing#Early_computers_and_the_Turing_test https://secure.wikimedia.

Org/wikipedia/en/wiki/Alan_Turing identifies the page and Early_computers_and_the_Turing_test is the anchor. The reason that Facebook and other Javascript-driven applications (like my own Wood & Stones) use anchors is that they want to make pages bookmarkable (as suggested by a comment on that answer) or support the back button without reloading the entire page from the server.In order to support bookmarking and the back button, you need to change the URL. However, if you change the page portion (with something like window.

Location = 'http://raganwald.com';) to a different URL or without specifying an anchor, the browser will load the entire page from the URL. Try this in Firebug or Safari's Javascript console. Load http://minimal-github.gilesb.com/raganwald.

Now in the Javascript console, type: window. Location = 'http://minimal-github.gilesb.com/raganwald'; You will see the page refresh from the server. Now type: window.

Location = 'http://minimal-github.gilesb.com/raganwald#try_this'; Aha! No page refresh! Type: window.

Location = 'http://minimal-github.gilesb.com/raganwald#and_this'; Still no refresh. Use the back button to see that these URLs are in the browser history. The browser notices that we are on the same page but just changing the anchor, so it doesn't reload.

Thanks to this behaviour, we can have a single Javascript application that appears to the browser to be on one 'page' but to have many bookmarkable sections that respect the back button. The application must change the anchor when a user enters different 'states', and likewise if a user uses the back button or a bookmark or a link to load the application with an anchor included, the application must restore the appropriate state. So there you have it: Anchors provide Javascript programmers with a mechanism for making bookmarkable, indexable, and back-button-friendly applications.

This technique has a name: It is a Single Page Interface.P.s. There is a fourth benefit to this technique: Loading page content through AJAX and then injecting it into the current DOM can be much faster than loading a new page. In addition to the speed increase, further tricks like loading certain portions in the background can be performed under the programmer's control.P.p.s.

Given all of that, the 'bang' or exclamation mark is a further hint to Google's web crawler that the exact same page can be loaded from the server at a slightly different URL. See Ajax Crawling. Another technique is to make each link point to a server-accessible URL and then use unobtrusive Javascript to change it into an SPI with an anchor.

Here's the key link again: The Single Page Interface Manifesto.

10 "However an application without this optimization is still crawlable if the web crawler wishes to index it. " Not really. The hash doesn't get sent to the server.

– broady Oct 17 '10 at 2:58 3 just for information: self.document.location. Hash provides the value of this hash – Kevin Oct 17 '10 at 10:19 8 The hash doesn't get sent to the server. Good catch!

– raganwald Oct 17 '10 at 12:08 1 The hash getting sent to the server is sadly client independent. Granted google may not currently send the hash to the server, and I'd be surprised if it did, but some things ( and some clients ) may send the # part anyway. ( Just like some web-clients will resolve the "../../" part of urls client-side, and others will ship them to the webserver as-is ) – Kent Fredric Oct 17 '10 at 9:47 9 This entire answer aside from the single-paragraph "pps" is redundant.

– Tomalak Geret'kal Oct 17 '10 at 18:56.

First of all: I'm the author of the The Single Page Interface Manifesto cited by raganwald As raganwald has explained very well, the most important aspect of the Single Page Interface (SPI) approach used in FaceBook and Twitter is the use of hash # in URLs The character! Is added only for Google purposes, this notation is a Google "standard" for crawling web sites intensive on AJAX (in the extreme Single Page Interface web sites). When Google's crawler finds an URL with #!

It knows that an alternative conventional URL exists providing the same page "state" but in this case on load time. In spite of #! Combination is very interesting for SEO, is only supported by Google (as far I know), with some JavaScript tricks you can build SPI web sites SEO compatible for any web crawler (Yahoo, Bing...).

The SPI Manifesto and demos do not use Google's format of! In hashes, this notation could be easily added and SPI crawling could be even easier (UPDATE: now! Notation is used and remains compatible with other search engines).

Take a look to this tutorial, is an example of a simple ItsNat SPI site but you can pick some ideas for other frameworks, this example is SEO compatible for any web crawler. The hard problem is to generate any (or selected) "AJAX page state" as plain HTML for SEO, in ItsNat is very easy and automatic, the same site is in the same time SPI or page based for SEO (or when JavaScript is disabled for accessibility). With other web frameworks you can ever follow the double site approach, one site is SPI based and another page based for SEO, for instance Twitter uses this "double site" technique.

Website shouldn't crash of fail due to disabled JavaScript. And trust me, javascript is disabled not just in outdated browsers but also by many security aware users who do not like executing random JS. – Roman R.

Mar 29 at 4:05.

I.e. It's not really a shebang but it just happens that # and! Are right next to each other?Right.

I always assumed the! Just indicated that the hash fragment that followed corresponded to a URL, with! Taking the place of the site root or domain.It could be anything, in theory, but it seems the Google AJAX Crawling API likes it this way.

The hash, of course, just indicates that no real page reload is occurring, so yes, it’s for AJAX purposes. Edit: Raganwald does a lovely job explaining this in more detail.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.