An existence that is parallel to our own. Often thought to contain replicas of ourselves in various or similar forms but never the same. There can be infinite Alternate Dimensions, but never one exactly like our own.
Dimensions are Alternate Realities, Times, Universes, and Lives all in one.
In an Alternate Dimension, I am a Dog.
In an Alternate Dimension, I am a Cat.
In this Dimension, I am a Human.