Easement in Gross means holder acquires a right to use the servient estate independent of his possession of another tract of land. The easement benefits the holder rather than another parcel.

An easement in gross for the holder’s personal pleasure (e.g., right to swim in the pond) is not transferable.
Easement that serves an economic or commercial interest (e.g., the right to erect billboards) is transferable.

Example of an easement in gross;
Frank grants Liz an easement to fish in his pond, which is located on Frank's privately owned property. As part of this easement right, Liz is also granted an easement to enter onto Frank’s property to go to and from the pond. While Liz may live next door, she may move miles away, and the easement follows her; NOT her property.

This is an easement in gross; Liz is the dominant owner; Frank is the servient owner; Frank owns the servient estate (with the pond on it). There is NO dominant estate.

The person who enjoys the easement over the other person’s property is called the "dominant owner", and that person’s land is called the "dominant estate ". The land subject to the easement is called the "servient estate ", and the owner of that land is referred to as the "servient owner".