SharePoint Web Application could be defined as an IIS Web Site specifically configured to run WSS sites.
So the question arises what is an IIS Web Site?
IIS Web Site could be defined as an entry point in the IIS Web Server infrastructure.
Default web site created listens for incoming HTTP requests on port 80. We could create additional web sites as well, having different port numbers or IP addresses. Every IIS Web site could be configured independently. For e.g. we could have Default Web Site allowing anonymous access and a second IIS Web site that uses integrated authentication.
Creating IIS Web Site
http://msdn.microsoft.com/en-us/library/tcywfea7(VS.80).aspx
Creating a Web site by using IIS Manager does not create content, but merely creates a directory structure and configuration files from which to publish the content. To publish the Web content, we can place content in the default home directory, or we can create a different home directory or virtual directory and place content there.
Creating or extending WSS Web application
http://technet.microsoft.com/en-us/library/cc287954.aspx
Using Central Administration application we could easily create web site which would be automatically configured to be a WSS Web Application. A new content database gets created for each newly created web application. Normally we would be having one content database per web application. However it is possible to distribute sites within a web application across multiple content databases.
Understanding Content databases
Creating multiple content database in a web application
http://trycatch.be/blogs/tom/archive/2007/06/21/multiple-databases-for-1-web-application.aspx
http://manish-sharepoint.blogspot.com/2009/01/creating-sitecollection-in-new-content.html
So what happens when a IIS Web Site is transformed to a WSS Web Application?
- WSS makes few entries into the IIS Metabase.
- Creates virtual directories which maps to 12 hive (installation directory\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\)
- _controltemplates – where user controls are kept.
- _layouts – has application pages in it.
- _vti_bin – dlls and web services repository
- _wpresources – resource file repository for Web Parts
- Adds WSS-specific web.config to the root directory of the IIS Web site.
- Extends routing architecture of IIS and ASP.NET to properly route all incoming requests through WSS runtime.
A single web application could have multiple site collection within it and each site collection has a top level site and could have multiple sub sites in it. A WSS site collection acts as a container of WSS Sites.
Bye ..
Nishant Rana's Weblog 
Hi Nishant,
It’s a good description and cleared out the doubt about SharePoint Web Application.
Thanks
Pradeep
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nice work !
can you plz let us know the possibility of ssl against site collections. i mean with in one web app ssl and non ssl top level sites.
——————-
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I have a question how can we create new webapplication or site on different ip address in sharepoint . is it possible. ?
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Hi, i could create the web application on SharePoint but still when i tried to browse it, it says : Internet explorer cannot display the webpage.
Any suggestions? Thank you.
Mei.
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Thank you for the consistent quality in content and sharing one of your favorite post.
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Hi Nishant,
Hmmm… one thing bloggers never like to admit is when they DON’T know something, yet the irony is this – most people who are looking for answers might NOT actually know the answer they seek… but they DO know when they see something which DOESN’T answer their question.
That said, what do you think of your answer?
Me? I’ll just say that after reading your article, I may have learned a few things about what happens to an IIS web site when it becomes “extended”… but I find myself still looking for an answer which I’ll recognize as both accurate & complete.
😉
Looks like it’s back to the textbooks for both you & me…
😉
Don’t stop posting – that would be a greater sin. But if you suddenly realize your own understanding is lacking (as I am mine), please acknowledge t amongst us your colleagues.
Very best regards,
-Mark
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Thanks Mark, I do understand your point. This article simply reflects whatever i came to know about the topic from various resources and i thought i should share. I haven’t mentioned anywhere that this is the most complete information or i am expert in the subject matter.
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