Select an item in the item list (item list: In the main Outlook window, the list of messages, contacts, tasks, or other items.You can assign an item to a standard category, such as Family or Travel, or to a category that you create. Because categories are color-coded, when you view the item list, it's easy to see which items belong to which category. You can organize your messages, events, contacts, and other items (items: Units of information in Outlook, such as e-mail messages, calendar events, contacts, tasks, and notes.) by assigning them to categories.