Banner

Use a fixed banner to alert the user about significant information. Appearing from the top and pushing the content down, the message will :

be closed by the user.
disappear after a few seconds.

Use a float banner to transmit a message with less impact on the user (e.g.: an action confirmation). The banner should not interrupt the user, but will appear within his field of vision. Consequently, the message and its frequency must be adapted.

A float banner can either stay for “x” seconds or require the user to perform the action requested.

Prefer concise and explicit messages.

Avoid using two lines of text for a message. Never show more than one fixed banner.

Always show at least a title or add secondary text or an icon to provide more details. You also add a call to action if the user can perform an action quickly.

Be careful with using too many floating banners at the same time, it increases the cognitive load for the user.

Always use a description and propose actions when there are several floating banners of the same type to keep the user informed.

Avoid technical and unexplicit messages for the user.

Visual variants

Use the color system to give meaning to the message and allow users to consider the importance of the message.

Success messages: give a positive message to the user following a successful action.

Warning messages: give a message of vigilance in order to inform the user of a potential error or a recommendation to finish an action.

Error messages: give a negative message following an error during an action or improper use of the system and provides information for finishing the task.

Information messages: give some neutral contextual information to the user to help understand an action or to announce a minor change.