Information and the operation
of user interface must be
Easy to understand
Information and the operation of a user interface must be understandable: Users must be able to understand the information as well as the operation of the user interface.
Under this principle you will find guidelines relating but not limited to:
- Readable: Make text content readable and understandable.
- Predictable: Make Web pages appear and operate in predictable ways.
- Input Assistance: Help users avoid and correct mistakes.
Let’s see how to apply the guidelines to our products
3.1. Make text easy to understand
3.1.1 Language of page
Identify the language that the of the page is written in (English for example).
3.1.2 Language of parts
If the page has in more than one language (for example, if a page in English has a button labelled in Welsh), identify the language of each part in .
3.2. Make things appear and behave in consistent, predictable ways
3.2.1 Changes on focus
Just navigating to an interactive control with the keyboard shouldn’t trigger any action, and shouldn’t move the keyboard focus somewhere else.
3.2.2 Changes on input
Just changing the state of a form input (like a radio button) must not cause anything surprising to happen, like submitting a form, significantly changing the on the page, or moving the keyboard focus.
3.2.3 Consistent navigation
Make sure that navigation controls that appear on multiple pages (like links in a header) are consistent across pages.
3.2.4 Consistent feature names
If a user interface component exists on multiple pages, make sure that the way it looks and the way it is named is consistent across pages.
3.3. Help people avoid and correct mistakes
3.3.1 Error identification
When someone makes an error while filling in a form, describe the error with text and clearly identify where the error is.
Provide labels to make it clear how users should fill in a form, and optionally provide extra hints to help them avoid errors.
3.3.3 Error suggestions
When someone makes an error while filling in a form, give them suggestions on how to correct it.
If users are making a legal commitment, a financial transaction or updating personal data, give them a way to review and check that the information they’ve entered before submitting it.