Google Compute Engine is the Infrastructure-as-a-Service (IaaS) component of Google Cloud Platform and provides on-demand cloud infrastructure for general purpose applications with a variety of server sizes, regions, and operating systems. It lets you launch virtual machines on demand, and also lets you reserve instances with automated per-second pricing.
Incoming and outcoming network traffic going through your virtual machines in bytes.
The amount of bytes written and read from the disk in a period of time.
The percentage of your CPU resources being used.