What does extending a Web Application to another zone mean?

Question

I have read the following definition regarding web application zone types (Default, Intranet, Internet, Custom, Extranet):

When you extend a web application to one of these zones, you actually create a new separate IIS website that serves the exact same content as other websites in your web application, but they will each have their own unique URL to connect to and can also use different authentication methods.

What does it mean by

serves the exact same content as other websites in your web application

Does it refer to the same content database, but a different site collection?

And what does it mean by

you actually create a new separate IIS website

Does it mean that when I extend a Web application to a new zone, for example Internet, it creates a new Site Collection?

From what I understand, the zones are useful when you want different URLs and authentication methods for the same content. By content does it refer to the same site?

Wouldn't that be unnecessary? I mean, even I have different authentication types for Intranet and Internet users, the content the users access is the same, so an Internet user with anonymous login sees exactly what a Form Based Authentication login user sees.

Answer 1

When you extend a Web Applications

It will create another IIS sites and use the same App Pool as Main Web App But using the Same Content Database and no new site collection will be created, as it will use the same content. Let me explain with a simple Example.

I have requirement to create a Portal which will be used by our internal User(intranet) and external User as well. Internal User have full control on the site but externally we want give few contractor to access the site with authentication and rest of world use anonymous access to our public data. I dont want to give access external user to my active directory( to create a new User), rather i want them to authenticate different method i.e FBA. External User have access the different url then the internal. In this case the best thing is:

I create webapplication in default zone with windows authentication, Now i will extend the web application to different user and configure the FBA authentication method and different URL(Which will be public URL). Now i will setup the secularist on the Content, enable anonymous on the content which we want to share with rest of world.

This method simplized the publishing thing, you create the content once but with security you secure your content.