This article is for accounts created before the 25th of June, 2016.
Contacts are used for Basic Alerting in the different checks to send notifications. Contacts can contain information for different methods of contact, such as email, phone number and connected devices. This is available under under Alerting > Contacts.
Users are part of the BeepManager Incident alerting system. The other parts include Alerting Endpoints, Incidents, Incident Alerts, Incident Log, Schedules and Maintenance Schedules.
Users and Alerting Endpoints are connected to checks via Alert Policies. Users can contain information for different methods of contact, such as email, phone numbers, webhooks and connected devices. Users can also be assigned responsibility for incidents. Alerting Endpoints can have all the same alerting methods, except for mobile devices.
Incident Alerts are named so because when a check set up for Incident alerting goes down, an incident is logged, and responsibility for it is assigned to a User or an Alerting Endpoint. Incidents are used to keep track of responsibilities for the check that changed status (went down).
Alert Policies are used to set up who is first assigned responsibility, setting delays for the notifications, order for sending out notifications and reassigning the incident to other Users or Alerting Endpoints with several steps. You can set up the Alert Policies to send repeated notifications.
Schedules exists as well, which can be used to set up different Users and Alerting Endpoints who have duty at different times. These are also connected in Alert Policies and are used instead of a User or Alerting Endpoint.