Notification Elements
Notifications are third-party elements within the Craft ecosystem.

Tabs
Each individual Notification consists of four parts, separated into tabs...

Meta
Contains the native Title field, plus any custom fields you've attached.
Event
Each Notification is tied to a specific event within the Craft system. When that particular event is triggered, the corresponding message will be sent out.
Message
Write a custom message for each Notification. Within the message's Twig template you can use a series of special variables about the event which triggered it.
Recipients
Select which recipients will receive each Notification. The available options for recipients depends primarily on which message type was selected.
Fetching Notification Elements
Whether working in Twig or PHP, you can use the following helper functions to fetch Notifications...
Twig
{# Use an element query for Notifications #}
{% set notifications = notifier.notifications.all() %}
{# Get a specific Notification by its ID #}
{% set notification = notifier.getNotification(id) %}PHP
use doublesecretagency\notifier\helpers\Notifier;
// Use an element query for Notifications
$notifications = Notifier::notifications()->all();
// Get a specific Notification by its ID
$notification = Notifier::getNotification($id);