Columns
Applies to: SharePoint Foundation 2010
A site column is a reusable column definition, or template, that you can assign to multiple lists across multiple SharePoint sites. Site columns decrease the amount of rework needed and also helps ensure consistency of metadata across sites and lists. Use the links in this section to learn how to create, customize, and update site and list columns.
Adding Columns in Content Types to Lists
Enforcing Uniqueness in Column Values
Lookups and List Relationships
How to: Add a Column to a List
How to: Add a Column to a Site