In Jainism, the universe (Lok) is one, but it is divided into three main parts (3 lok):

1. Urdhva Lok (Upper World)

- The heavenly regions. - Abode of devas (celestial beings). - Above all of this, at the very top, is Siddha Shila, where liberated souls (siddhas) stay forever.

1. Madhya Lok (Middle World)

- The region where humans, animals, plants, etc. live. - Our Earth is part of Madhya Lok. - Only here can a soul do spiritual effort and attain moksha.

1. Adho Lok (Lower World)

- The hellish regions (narak). - Beings here suffer according to their bad karma, but not forever; after karma finishes, they are reborn elsewhere.

Outside this Lok is Alok (empty space, no souls, no matter).

So, when we speak simply:

• There is 1 Lok (universe), divided into 3 main lok: Urdhva, Madhya, and Adho.
• At the top of Urdhva Lok is Siddha Shila, the abode of liberated souls.