First and foremost, a site collection is a (hierarchically arranged) logical container for grouping sites. From there, you need to know that the top-level site in a site collection is often a portal site that aggregates content from subsites - although this isn’t required - and that a Web application can host multiple site collections.

The number of site collections you create depends on many factors. Every site in a collection shares navigation, security and permissions, templates, and content types. You should plan to group together sites that need to share these items and make them a site collection.

Before you create a site collection, gather several pieces of information - including these:

• Path: You can determine the path to your site collection before you create it. The servername in the URL is determined by the Web application. Your two default options are to create the site collection at the root of the URL or at the sites path. Subsites are created below this URL.
• Administrators: You need to choose primary and secondary administrators for the site collection.
• Web application: You have to decide which Web application should host the site collection.
• Site template: A site template is a boilerplate for creating SharePoint sites. When you create a site collection, you create the top-level site in the collection. You need to select the template for the top-level site. See the next section, “Configuring Web Applications and Site Collections.”
• Quota: You may choose to select a quota that defines limits on the sizes of the sites created in the site collection.

To create a site collection, follow these steps:

1. Click the Application Management tab in the SharePoint Central Administration site.
2. Click the Create Site Collection link in the SharePoint Site Management section. The Create Site Collection page appears.
3. Using the Web Application drop-down menu, select the application where you want to create the site collection. To create a site collection, follow these steps: Click the Application Management tab in the SharePoint Central Administration site. Click the Create Site Collection link in the SharePoint Site Management section. The Create Site Collection page appears. Using the Web Application drop-down menu, select the application where you want to create the site collection
4. Type a title and description for the site collection.
5. In the Web Site Address section, type a URL for accessing the top-level site in the site collection. Your default options are to use the root path, which is depicted by a forward slash (/), or to use the /sites path. You can add more paths as needed.
6. Select a template to use for the top-level site in the site collection. Your template options depend on whether you’re using Windows SharePoint Services or Microsoft Office SharePoint Server 2007. WSS offers collaboration templates for small teams and project groups such as Team Site and Document Workspace. MOSS 2007 includes additional templates that are suitable for divisional portals and enterprise uses. Some MOSS 2007 site templates, such as those for collaboration and publishing portals, can only be used when you create the top-level site in a site collection. Any other site templates can be used to create sites within the site collection hierarchy.
7. Type or select the primary and secondary site-collection administrators. The accounts you use here are from your authentication provider (for example, Active Directory). You should generally specify two site-collection administrators. Having a backup administrator ensures that administration e-mail doesn’t go unanswered in the event the primary administrator is on vacation.
8. Select a quota template in the Quota Template section. See Chapter 18 for more information about using quota templates to monitor and control site usage.
9. Click OK. The Operation in Progress page appears. Wait while the site collection is created. The operation can take a few minutes while the content is added to the database. The Top-Level Site Successfully Created page appears. The URL for the top-level site appears in the page. You can click the link to test the site. Click OK to return to the Application Management page.