Master Categories can be applied to Activities, Notes or Documents within Redtail. Note: this is distinct from the Category field you can apply to individual Contacts.
To add a new Master Category to your database, first go to Manage Your Account:
Then, select Manage Database Lists:
The body of the Manage Database Lists page is controlled by which List you have selected in the Manage Lists column on the right:
After you've clicked Categories under the Activities and Notes header, your page will display this list. Below is an example Categories list:
You can add new Categories by clicking the add button in the top right corner. You'll then see the below modal:
Just type in the name for your new Category and click Add Category.
Those Categories that have been manually added to your database have both Edit and Delete options available from their Actions menu, meaning you can edit their name or delete them entirely.