SharePoint 2016 introduced Webhooks for List Event Handling. Webhooks are much better than Remote Event Receivers.
Webhooks are enabled on SharePoint list items
Webhooks allow developers to Subscribe list item changes
Webhooks support only Asynchronous events
Webhooks requires a Target URL
You need an Office 365 Subscription to test Webhooks.
You need to create a List Event subscription on the required List
You need to setup a Server URL to host the Webhook URL
Subscription can be enabled with an Expiration Date
The class need to be inherited from SPWebhookNotification class.
The class should implement properties for SubscriptonId, ClientState etc.
Http Post attribute should be used for the receiver method.