The Planescape campaign setting is a big place. Not only are the Outer Planes and the Prime Material Plane basically infinite, but so too are the Inner Planes. Though at least the Inner Planes are more straightforward. If you're looking to get a primer on the Inner Planes, then this is a good place to start. I hope you enjoy diagrams and pictures of fantasy landscapes, because I got lots of em. If you noticed that I basically copied my video description from my Guide to the Outer Planes video, then A+ for attention to detail. Does anyone even read Youtube video descriptions anyway?

0:00 Intro to the Inner Planes
5:32 The Plane of Air
8:03 The Plane of Earth
10:13 The Plane of Water
11:43 The Plane of Fire
14:25 The Plane of Positive Energy
16:04 The Plane of Negative Energy
17:41 The Para-plane of Smoke
19:00 The Para-plane of Magma
20:24 The Para-plane of Ooze
21:48 The Para-plane of Ice
23:04 The Quasi-plane of Lightning
24:48 The Quasi-plane of Radiance
26:01 The Quasi-plane of Mineral
27:10 The Quasi-plane of Steam
28:24 The Quasi-plane of Vacuum
29:50 The Quasi-plane of Ash
31:03 The Quasi-plane of Dust
32:25 The Quasi-plane of Salt
33:30 End

Source:
Planescape campaign setting book: https://www.yumpu.com/en/document/rea...