Already in 1882 the word interface appeared being assembled by scientists and doctors describing the boundary between two chemicals like a water-oil-interface. “However, Victorian era physicists employed “interface” to describe sites where heat, light, and electricity flowed between different materials. How was the 19th century conception of interface similar to or different from our contemporary notion?”¹

Shifting from natural to computer sciences, the term got already used in multiple disciplines in the 19th century by “Sir William Thomas. An acclaimed scientist with influential theories on electricity and the laws of thermodynamics, Sir William was knighted for his work on the transatlantic telegraph. In addition to his integral role with the formation of information technology infrastructures, Sir William was the central figure using and actively promoting the term “interface” to describe natural phenomena.”¹

Even though interfaces became an important term for the information technology early on, there exist distinct differences between the term used by Sir William as a physical phenomenon and the information technology in computing. “For example, Sir William frequently used ”interface” to describe his theory of light, and this theory was based on his understanding of how signals traveled through a telegraph wire. 19th century physicists such as Sir William were not isolated from then contemporary revolutions in communication technology. On the contrary, they were working to better understand problems such as the dissipation of energy and the relationship between conduction and signal velocity. In this context, interface was a useful signifier for describing the transfer of energy that could also be used to describe the transmission of information. “¹

In contrast to Williams understanding and other scientists and Doctors of the time, the digital interface like the GUI goes beyond being a boundary that needs to be interfaced but is actively participating in interfacing itself, becoming less a boundary but more a space “in between”.

Schäfer argues “that the 19th century conception of interface is not a discrete prehistory to its conception in the 20th and 21st century. Rather, I make the case that the use of “interface” from 1868 to 1888 reflects a shared set of assumptions for modern notions of communication.“¹ But it should also be noticed, that the multiple concepts used and rearranged over the 150 years of the terms existence there is a distinct shift from the 19th and 20th to the 21st century. The Interface as a natural phenomenon as described in chemistry and physics with electricity does not account for the graphical user interface displayed in this keyword. The interface of the 21st century becomes an agent in human communication as well as machine – machine interfaces become a constant in our lives, consciously or not.