Across the top of all web app pages (including the login page) and the top of the home feed of the mobile app, your institution can opt to display a banner announcement to your users. The announcement appears for a user until they select the "X" to the right of the banner to close it. Once closed in the web app, it will not reappear unless the user's web browser cache is cleared or the announcement is updated. Once closed in the mobile app, it will not reappear during the current mobile session, but will reappear on subsequent mobile sessions.
The announcement can be customized in Narmi Command under Institution Settings > Announcement.