How many types of authentication modes are there and what are the Types of available authentication modes in dot net 2005?

ASP.NET implements additional authentication schemes using authentication providers, which are separate from and apply only after the IIS authentication schemes. ASP.NET supports the following authentication providers:
• Windows (default)
• Forms
• Passport
• None
To enable an authentication provider for an ASP.NET application, use the authentication element in either machine.config or Web.config as follows:
<system.web>
<!-- mode=[Windows|Forms|Passport|None] -->
<authentication mode="Windows" />
</system.web>
Each ASP.NET authentication provider supports an OnAuthenticate event that occurs during the authentication process, which you can use to implement a custom authorization scheme. The primary purpose of this event is to attach a custom object that implements the IPrincipal Interface to the context.
Which ASP.NET authentication provider you use typically depends upon which IIS authentication scheme you choose. If you are using any of the IIS authentication schemes other than Anonymous, you will likely use the Windows authentication provider. Otherwise, you will use Forms, Passport, or None.