When is a technology a medium

A technology becomes a medium through many complex social transformations and transitions: 

 Here we might take the much-considered case of photography.

Clearly there is a photographic technology; one in which optical and mechanical systems direct light onto chemically treated surfaces which then become marked in relation to the way that configurations of light fall on that surface. This, however, is not a medium.

The manufacture of silicon chips, a technical process upon which the manufacture of computers now depends, uses this photographic technology. It is used to etch the circuits on the microscopic chips. This is a technological process - a technology at work.

However, another use of the photographic technology is to make pictures - to depict persons or events in the world. This may also be a technology at work. However, when it is said that these pictures or images provide us with information, represent an idea, express a view, or in some way invite us to exercise our imaginations in respect to the contents and forms of the image, then we may say that photography is being used as a medium.

Or, more accurately, the technology of photography is being used as a medium of communication, expression, representation or imaginative projection.

On this line of argument, a medium is something that we do with a technology.

Clearly, what we do needs to be of an order that

• the technology can facilitate or support
• but it does not necessarily arise from the technology itself.

Having an intention for a technology is not synonymous with the technology per se.

A technology becomes a medium through many complex social transformations and transitions: 

it is, in Williams's reading, profoundly the product of culture and not a given consequence of technology.

Martin Lister / Jon Dovey / Seth Giddings / lain Grant / Kieran Kelly: New Media: a critical introduction, Routledge, 2009