Ivo Kurzemnieks Added and updated:

• https://www.zabbix.com/documentation/4.0/manual/api/reference
• https://www.zabbix.com/documentation/4.0/manual/api/reference/task
• https://www.zabbix.com/documentation/4.0/manual/api/reference/task/create
• https://www.zabbix.com/documentation/4.0/manual/api/changes_3.4_-_4.0

Current description of a Task in API documentation is:

This class is designed to work with tasks.

And that's it. I don't think this is enough to understand for a user what exactly is Task and why would any one want to use it. Re-opening to improve.