How do I determine the ID of the site collection in SharePoint?

Of course, the methods for determining these IDs can be retrieved from the database or output using the object model, but the simplest method is to view them at a few clicks on the interface.

 

1. Open the management center site and open the application management tab.

2. Click site collection administrators.

3. Select the site collection you want to view. In the IE address bar, you can see the guid of the site set.

 

 

Source:

Http://hristopavlov.wordpress.com/2008/10/20/a-very-fast-method-to-get-the-site-collections-web-structure/

 

Link:

How do I determine the ID of a Sharepoint list?

Http://www.cnblogs.com/awpatp/archive/2010/01/28/1658714.html

How to determine the Web Application ID of SharePoint

Http://www.cnblogs.com/awpatp/archive/2010/02/19/1669368.html