Forms are a collection of input fields and design patterns that collect and process different types of qualitative and quantitative data input from users. Can include the visible user interface components as well as the logic required for controlling aspects of its behavior such as form validation, data retrieval and storing of incomplete forms.

A form usually contains labels which describe it's various input fields and controls. In the case of complex concepts, contextual help at the control-, field-, or form-level may be provided to assist users. A form may consist of a single label and control, or may be an extensive set of inputs.

The layout of a form is just as important as the content it contains. Users must be able to easily determine which inputs are required or optional, which labels or messaging goes with which field or control, and how to properly complete each field. Grouping, ordering, and use of space are very important in form design. The form typically ends with the submit button or control that determines the information that is to be grouped together for submission or further processing.

Validation of the input must be carried out prior to the data being submitted to the application so that the user can change their input. (See , )

Form also refers to physical questionnaires on paper in which to fill in data by writing or printing.