Alert notifications are the most important notifications you need to know about, more important than notices. They are concerning you directly and most of them will need an action from you. There are different types of alerts.
The notification "badges" are the icons at the top of all wiki pages that inform users about new or unread notifications.
When users have unread notifications, the badges display the number of unread messages, up to a maximum of 99. When a user has messages that are "unseen" (meaning a notification arrived since the last time the user checked their notifications), the badge changes color: red for unseen Alerts, blue for unseen Notices.
Badges are grey when you have zero unread notifications, or you have unread but not new notifications.
Also known as: Bundled notifications
When multiple actions or events affect the same item, such as a single post or a page, the system may generate a "bundled notification." This is a single notification that informs the user about multiple events. E.g., "Your post in 'Topicname' was edited multiple times." (See Expandable bundle, below.)
Cross-wiki notifications are displayed on both panels, and regroup the notifications from other Wikimedia Foundation hosted wikis. This enables you to receive notifications about Commons when you are on Wikisource, for example. (Learn more)
An alternative form of Collapsed notification. When multiple actions or events affect the same item, such as a single post or page, the system may generate an "expandable bundle" of notifications: in this case, one main notification explains that multiple events have occurred (e.g., "5 new topics created on Pagename".) An arrow allows the user to expand that group and see the individual notifications pertaining to each event, or to "Collapse" and hide the bundle again.
The gray text beneath the Notification header provides details that help users better understand the message. This is frequently an excerpt—e.g., from a post or topic summary. This element is optional. (more information)
The bold title that tells you the main information about the notification. E.g., "Your post in 'Topicname' was edited." (more information)
Also known as: Flyouts, Dropdowns
The notification panels drop down from the top of a wiki page when you click on one of the "badges" (for either "alerts" or "notices"). They provide a quick view of your most recent notifications; each panel shows up to a maximum of 25 alerts or notices, respectively. "Unread" notifications, sorted by date, are displayed first, followed by "read" notifications.
Notices notifications are less important notifications than alerts. They concern you, but probably don't require an immediate action. There are different types of notices. In some languages, "Notice" is translated by "Notification".
The three-dots menu hides more information and other items that can be useful to take action.
The three-dots menu is optional and is sometimes not displayed.
When a notification is not read, it is highlighted by a pale blue background. The blue dot also highlights that notification.
Mentions are a type of notifications. It is possible to both mention people and be mentioned. (details)
Beneath the main header and body of most notification, one or two small icons may appear, accompanied by labels. These are the "secondary links." In addition to linking to relevant destinations, these links are also useful for displaying important information, such as the username of the person who performed the action that triggered a notification. (It's good style to avoid repeating such information in both the header and the links.)
A trigger is one or many conditions which will ask the system to deliver the notification.