[Observium] graph color

Guys,

This might be a general RRD question. So in almost all graphing, we have those shaded color area and solid color line. Although I have a general idea on what they mean, I still want some official explanations regarding their meanings. Thanks.

I attached a cpu usage graph here as an example. We have grey shaded area, and solid red line.

I guess the red line is some kind of moving average? While grey shows spikes? Or how else could I inteprete this?

Thanks a lot.

Zhenhui[cid:2CB03DFE-FFA0-4DA8-9438-EB2732F92119]