This process is broken down into seven layers; Application Layer, Presentation Layer, Session Layer, Transport Layer, Network Layer, Data Link Layer, and Physical Layer. When a person communicates to another person on a network the information passes through these layers.
Ptolemy was an astronomer and mathematician. He believed that the Earth was the center of the Universe. The word for earth in Greek is geo, so we call this idea a geocentric theory.
It is generally thought to have begun with a book, On the Revolution of the Heavenly Spheres by Nicolaus Copernicus in 1543. This book was the first to postulate that the Earth was not the center of the Universe.