Act of traveling from world A to world B without being completely disconnected from world A.
The difference between a dream and a drift is the location of the physical body. Dreaming is a mental procedure, i.e. going to different places by power of your mind without your body leaving the world A; whereas drifting needs someone to transfer her body to world B, in other words, when you drift, your body vanishes from world A and arrives in world B.
In Eltts stories, people use different means and methods to initiate a drift and transfer their bodies between parallel universes. For example Elitshia Eltts and Illenis Inkks's favorite method is using steam, mists, fogs and alike as portals to other universes and they call it "Jumping".