What is Gauge.startTimer for and how to properly use it?

Question

As I understand, the Gauge counter is a value that changes over time without saving somewhere when every change of the counter (dec(x) or inc(y)) was and the labels of every call to dec or inc.

Please correct me if I'm wrong.

Questions

• What exactly Gauge.startTimer does?
• What will be sent to prometheus?
• When to use it?
• How does it saves the data locally in my application?