USB Type C Power Delivery Feature

I found some ASUS laptop with USB Type C Power Delivery feature.

Laptops list:

ASUS ZenBook 3 UX390UA

ASUS ZenBook 3 Deluxe UX490UA

ASUS ZenBook Flip S UX370UA

These are the devices only found with Power Delivery Feature and also explicitly mentioned in the ASUS specification description weblink.

But, I can't find the clear idea about this feature.

I have questions like

What is Power Delivery in USB Type C?

is it used for charging the laptop or externally connected the peripheral devices or both?

if both, how much power can we get from laptop to externally connected devices?

USB Type C support 100W power delivery, so can we get that much?

what are the power ranges we can get from that?