Custom attributes can be created in Settings > General > Custom Attributes. Custom attributes allow you to tag/group your audience in specific ways. For example, if you want to distinguish your weekly email list from your donor email list, here is where you create tags for those groups. You can create an unlimited amount of custom attributes. To add a custom attribute select "New Custom Attribute" on the top right corner of your screen. There are seven types of attributes.
Radio: This option allows you to set one value per profile (i.e. Favorite Color? Red OR Blue).
Checkbox: This option allows you set more than one value to a single profile.
Text: This option allows you to type notes or remarks about an individual with a free form text option.
Number: Add a number range to segment on different ranges.
Tag: This options allows you set one singular value to your entire data set.
Date: Add a date as an attribute to timestamp your audience.
Date time: Add a time and date as an attribute to timestamp your audience.
To keep your custom attributes organized and manageable you can create categories for them. For example, if you created a whole list for attributes for various event lists you can keep all that data in one category named, "Event Lists." Next time you log in you can quickly find that data within the category you created.
Custom attributes can be found through the Segment tool by clicking in to Segments > New Segment > Custom. Custom attributes are located in the Custom tab of every profile and both attributes and attribute categories can be edited at any time.