There are many different types of custom fields that you can allow attendees to add to their profiles. These range from HTML embeds to images to file downloads. Simple text, radio button or checkbox fields are also supported. There are no limits on how many Custom Fields you can add to your system or an attendee's profile. Additionally, choices or values input to each field can be changed at any time by visiting your account ('Account' in the top menu bar). 

Custom Fields are at their best when implemented before a system launch, allowing attendees to input values or make choices themselves during the registration process.

To learn more about Custom Fields, visit this article.

To learn more about adding a registration form to your event, visit this article.