A site column is a reusable column definition, or template, that you can assign to multiple lists across multiple SharePoint sites. Site columns are useful if your organization wants to establish some consistent settings across lists and libraries. You can share the settings across multiple lists and libraries so that you don't have to re-create the settings each time. For example, suppose you define a site column named Customer. Users can add that column to their content types or list. This ensures that the column has the same attributes, at least to start with, wherever it appears.

When you add an item to the list or library, you fill out a form in which each column is represented by a field. Each field is labeled with the name of the column. If you provide a description for the column, the description appears below the field. You can use the description to help team members fill out the form by explaining what kind of information goes in the field.

1. On the portal site home page, click Site actions, point to Site Settings, and then click Modify All Site Settings.
2. On the Site Settings page, under Galleries, click Site columns.
3. On the Site Column Gallery page, click Create.
4. In the Name and Type section, type the name that you want in the Column name box.
5. Select the type of information you want to store in the column.

The following table describes the types of columns that are available, by default.

Select this	To display this
Single line of text	Columns that collect and display small amounts of text in a single line, including text only, combinations of text and numbers, and numbers that are not used in calculations (such as phone numbers).
Multiple lines of text	Columns that collect and display one or more sentences of text or formatted text.
Choice (menu to choose from)	Columns that display a list of options.
Number (1, 1.0, 100)	Columns that provide a box in which you can type a numerical value.
Currency ($,¥, €)	Columns that provide a box in which you can type a monetary value.
Date and Time	Columns that store calendar or time-of-day information.
Lookup (information already on this site)	Columns that make it easy for you to select information that's already stored on a site.
Yes/No (check box)	Columns that store true/false information.
Person or Group	Columns that display the name of users or SharePoint groups.
Hyperlink or Picture	Columns that display a hyperlink to a Web page or display an image from the Web.
Calculated (calculation based on other columns)	Columns that display information that is based on the result of a formula. The formula can use information from other lists and columns, dates, or numbers. You can use standard mathematical operators.
Full HTML content with formatting and constraints for publishing	Columns that display the contents of the HTML Editor Web Part. Content and formatting constraints may be applied to the column.
Image with formatting and constraints for publishing	Columns that store links to images defined in the item properties. Each column displays an image, and optional formatting and constraints may be applied to it.
Hyperlink with formatting and constraints for publishing	Columns that store hyperlinks and display the names of hyperlinks defined in the item properties. Link formatting and constraints may apply.
Summary Links data	Columns that represent summary links for a page. Summary Links include a title, description, image, and URL and are used on publishing pages to present grouped links by using a set of shared styles.
Audience Targetting	Columns that display whether the item is targetted or not targetted. This column type requires the use of the Content Query Web Part.

6. In the Group section, select the existing group in which to store the new site column or create a new group to store the column.

The following table describes the groups that are available, by default.

Select this	To display this
Base Columns	Columns that are useful in many types of lists or libraries.
Core Contact and Calendar Columns	Columns that are useful in contact and calendar lists. These columns are typically used to synchronize metadata from client contact and calendar programs, such as Microsoft Office Outlook .
Core Document Columns	Standard document columns from the Microsoft Office core property set and the Dublin Core Metadata Set.
Core Task and Issue Columns	Columns that are useful in task and issues lists. These columns are typically used to synchronize metadata from client Task and Issue programs, such as Office Outlook.
Custom Columns	Columns that you add to suit the purpose of your list or library.
Extended Columns	A set of special-purpose columns.
Key Performance Indicators	Columns that are useful for displaying key performance indicator data.
Page Layout Columns	Columns that are useful for containing page layout information.
Publishing Columns	Columns that are useful for containing publishing information.
Reports	Columns that are useful for creating reports.

7. In the Additional Column Settings section, select the additional column settings you want. The options available in this section differ depending on the type of column that you select in the Name and Type section.
8. Click OK.