How to install Zabbix on an Ubuntu 14.04 VPS

Zabbix is the ultimate enterprise-level software designed for real-time monitoring of millions of metrics collected from tens of thousands of servers, virtual machines and network devices. It uses MySQL, PostgreSQL, SQLite, Oracle or IBM DB2 to store data.
Its backend is written in C and the web frontend is written in PHP. Zabbix offers several monitoring options such as checks that can verify the availability and responsiveness of standard services such as SMTP or HTTP without installing any software on the monitored host.