The People/Group field is used to link specific people to a task or list item. This field looks within the Active Directory and within the SharePoint Groups, the information of which ultimately is updated through Banner. Through workflows, the information in this field can be used to email information from SharePoint directly to specific people. Most prominently, this field is used for the “created by”, and “modified by” fields for all lists, and for the “assigned to” field for task lists. One caveat with this field is that one cannot sort or group by this field if “allow multiple selections” is activated.
Here is what Microsoft has to say about this field:
Use this column field type to provide a searchable list of people and groups from which people can choose when they add or edit an item. For example, on a Tasks list, a Person or Group column named Assigned To can provide a list of people that a task can be assigned to. The contents of the list depends on how directory services and SharePoint groups have been configured for the site. To customize the contents of the list, you may need to contact your administrator.
You can customize a Person or Group column in these ways:
Allow multiple selections Allow people to select as many options as they like or limit the number of selections to only one option.
Include or exclude groups of people Specify whether the list includes only individual people, or additionally includes e-mail distribution lists and SharePoint groups. For example, on a Tasks list, you might want to include only individual people to ensure that a specific person is responsible for each task. On a Projects list, you might want to include e-mail distribution lists and SharePoint groups to ensure that a team is associated with each project.
Limit the list to site users only Specify whether the list includes all people and groups in the directory service or only those people and groups who have access to the site as members of a SharePoint group.
Specify which information to display Choose which information you want to display about people or groups. For example, on a Contacts list for a large organization, you might choose to display a person’s name, picture, and details such as skills and expertise. On a Contacts list for a small team, you might choose to display only a person’s name or e-mail address.