SN74HC573A-Q1: Quiescent current question

I_I is the input leakage current, i.e., the current that flows into or out of an input pin. It is so small that it is often ignored.

I_CC is the quiescent current, i.e., the current that flows into V_CC and out of GND when the device is idle. When the device is switching, there is additional current, measured by C_pd. Additionally, there might be a noticeable output current, depending on the load. See [FAQ] How do I Calculate Power Consumption or Current Consumption for my CMOS Logic Device?