Alerts can be created/managed for OOB as well as Custom Entities in Dynamics 365 CRM

Create and manage announcement, rule-based and record based alerts

Alerts can be viewed as pop-ups, form notifications or sent as email to Dynamics 365 users

While scheduling alert levels can be categorized as Information, Warning or Critical

View the log of alerts read/dismissed by users in the Notification section

Add notification creation start date, notification creation end date and notification display end date

Alerts can be configured to be shown to a particular set of users and security roles

View alerts from anywhere in Dynamics 365 CRM through Notifications button on ribbon