Inline message
An inline message lets users know when important information is available or when an action is required.
When to use
- Detail that belongs to one field or one row and would crowd the layout if it were always visible.
- An explanation most readers do not need but some will look for.
- A warning tied to a single value, such as a setting that conflicts with another.
When not to use
- Anything the reader must read. Hiding it behind an icon means most people will not.
- A validation error. Those belong under the field, in the open.
- A message about a whole section. That is a section message.
- Help text that is always relevant, which should simply be written on the page.
Guidance
Do
Use it for the answer to a question only some readers will ask, and hint at the answer with the secondary text.
Don't
Do not hide an error behind an icon. Something blocking the reader has to be visible without being asked for.
Content
What to write, and what to leave out.
- The secondary text is a hint, not a label. Why? works, Information does not.
- Answer the question inside. A reader who opened it has already agreed to read.
- Keep it to a couple of sentences. Longer than that belongs on a page of its own.