Enabling Anonymous Access
In SharePoint, all users are authenticated. Internal users are authenticated by the network, and their credentials are used by SharePoint to determine what they can see and do. External users are prompted for their usernames and passwords when they first visit a SharePoint site. You can turn off that prompt by enabling anonymous access.
Anonymous access allows SharePoint to impersonate a built-in account administered by IIS. That account provides limited access to content within SharePoint. You enable anonymous access when you want to share the content in a site or library with the entire company or, if the server is connected to the Internet, the entire world.
To enable anonymous access:
Navigate to the Central Administration site.
Click Application Management, and then click "Authentication providers" under the Application Security heading.
Click the Default link, and then select "Enable anonymous access" and click Save.
Navigate to the top-level site and click Site Actions → Site Settings, and then click Advanced Permissions under the Users and Permissions heading.
On the toolbar, click Settings → Anonymous Access. SharePoint displays the Change Anonymous Access Settings page.
Select the level of access to allow and click OK.
Allowing anonymous access to the entire web site lets everyone view the home page and all lists and libraries that are not specifically restricted by unique permissions; allowing anonymous access to lists and libraries grants access to lists ...