In addition to the variety of preexisting fields designed to capture demographic information, you can also create custom fields to ask any question you'd like.
Text Inputs allow a consumer to enter in any text that they want with the onscreen keyboard
Single Select and Multi Select are multiple choice entries where the participant chooses between several options defined by you. Single Select only allows one to be selected and Multi Select can be configured to any number of allowable selections.
Checkboxes are simple Yes/No options
After you've chosen what type you want to create, the Add Survey Item dialogue pops up.
Survey items are saved by unique keys that differentiate one survey item from another. In a participant's data, each survey item appears in a separate column and every new survey item creates a new column. Since creating many unique survey items can quickly create many rows, it is encouraged to reuse survey items whenever possible. For this reason, all survey items in a brand are accessible to each of it's campaigns. The "Use Existing Question" Dropdown displays all relevant survey items one can use.
Additionally survey items are persistent and once created, if you edit a survey item, you edit it in all the places it is used. While cosmetic details like the language can be changed, things like the number of options cannot be. This is because Participants could contain data from a survey item which gets changed later, which could compromise the quality of your participant data.