By customizing lists and libraries, you are able to tailor your lists, whether they are created from a template or as custom lists, to match your needs. You can add columns to track the information that is important to you, create custom lookup lists as centralized references to other lists and set item-level security to secure each item appropriately.
Custom columns allow you to track the information that is important for you. With list items, the additional columns are customized so that you are tracking the information that is important to the task, announcement, event, or other list type. With documents, columns provide the additional metadata about the document so that it is easy to find, categorize, and track.
With every column, you have the opportunity to suggest default values. Default values provide a suggested entry for a field but can be replaced by whatever the user types. For some column types like choice columns, the first choice option is automatically populated in the default value field so if you would like a different default value or none at all either enter that default value or clear the field. You can also suggest a default value that is a calculated value like [Me] for a single line of text field which will automatically enter the user name of the creator of the item in the field.
For each column, you also have the option of making it a required column. This setting ensures that the user cannot ...