Besides List and Library Columns, SharePoint also gives us the option to create Site Columns. What are they and when and how would we use them?
In a nutshell, Site Columns are columns we create on a site, they are not specific to a list, and the site columns are available to its subsites.
To illustrate this map a little more:
Each of your department sites can be considered a “Top Site” and thus any site columns you create within your main department sites can be reused throughout any subsites you create.
However, our main division site is also a “Top Site” and thus all of the department sites underneath it are subsites of the divisional top site. Therefore, any site columns created at the division level, will be available to all department and committee sites, as well as their subsites. This is where SharePoint can get pretty powerful, and one reasons it’s important that the departmental site owners learn about SharePoint and work with your SharePoint Administrator to think through the overall departmental and division-wide data needs.
Creating a site column
While a number of site columns should probably be created at the divisional level, not all of the site columns would be of use to everyone, in which case they are best to live at your own department top site level.
To create a Site Column, you need to go to Site Settings (under the gear), and within the Web Designer Galleries section.
Advantages of Site Columns
They can be reused by multiple lists and libraries within a site and its subsites. They can help “normalize” data by having the column configurations centrally managed, which can make it easier to update data as needed, such as departmental name changes. You don’t need to hunt for the lists containing these types of columns. They are updated in one central location within either your department top sites, or at the division level.
Disadvantages of Site Columns
There is a bit of a learning curve to setting these up. They are not as intuitive to create as list/library columns and you need full control access to set them up. They also require some additional thought as to divisional data architecture each time they are set up.