Use a radio button group to provide users with a short (<5 items) list of choices from which they must select one.
Default radio buttons with a preferred selected value. If the user needs to be able to not select any option, use checkboxes instead.
The "Compact" layout option should only be used for radio groups containing short choice labels that are not likely to wrap onto the next line.
Use a checkbox group to provide users with a short (<5 items) list of choices from which none, one, or many items may be selected.
Use a single checkbox to provide users with a Boolean toggle.
The "Compact" layout option should only be used for checkbox groups containing short choice labels that are not likely to wrap onto the next line.
Use a dropdown to provide users with moderately-long lists of choices from which one or many may be selected, depending on configuration.
Use radio or checkbox groups for shorter lists, so all choices can easily be seen by the user.
Sort dropdown lists in a logical order, such as alphabetical.
Use pickers when browsing through a longer list is impractical.
Select the appropriate paragraph height ("Short", "Medium", or "Tall") based on the expected length of user responses.
Use the "Short" paragraph height in editable grids to align paragraphs with dropdown, number, and text inputs in adjacent columns.
Use instructions to display important content that is essential to completing the task.
If the content should always be visible, use instructions as opposed to a help tooltip or placeholder.
Consider using instructions when a field label becomes too lengthy.
Consider using a help tooltip instead of instructions for content that does not need be to read each time a user views the form.
For example, a help tooltip is appropriate for showing instructions that are most useful to new users.
Use placeholder text to describe the correct input format or provide a brief hint to assist with value input.
Placeholder text should not replace field labels.
Use placeholder text for picker components to provide a distinction from regular text inputs.
In general, use sentence case capitalization and keep the message as short as possible.