Postphenomenology is the study of human-world relations as per mediated by technology and specifically, technological artefacts.
There can be no technology apart from human beings, which is the big philosophical truth claim. Technology exists to assist human beings, to enhance their experience, to help navigate, control and interpret the natural world in which they are situated. Therefore, it really is about the humans’ relationship with their environment, but much more than that, their world (at that given time and space, as perceived by them), that makes technology an inevitable necessity, and so must exist between them in some form or fashion.
I simply looked out through my office window and I immediately thought of what I saw as a great example as there was some construction work taking place. Take for instance, when a human whose profession is that of a construction worker gets inside the digger or any other powerful machinery, their world quite literally (assuming they corroborate this claim if I ask them (elicit descriptive account of their first-person, subjective experience), transforms their world by simply mounting the specifically designed technology (in this case, the digger), from what it was even a few moments prior.

I can imagine this, as I too have the body of a human being, (Merleau-Ponty’s body schema), that my perspective, my immediate literal field-of-view as perceived by my eyes, would change in that I will be at least one metre or two off the typical plane on which my two feet (the extent of my schema) are usually grounded upon. I will be up high, and the view there is different. I would be able to see what is beyond a six-foot-high fence, and see other things that would have been obscured from my knowledge, awareness, and consciousness, even. Thus, my perceptual spatiality and temporality are transformed. This is but a component of a wider, larger co-constituted world that the digger technology brought about.
I could easily bring into this discussion the other changes to one’s lifeworld that transpires, such as the immediate acquisition of power (in its physics definition, the rate at which work is done or energy is transferred). This seems frivolously obvious, one might easily say, a simple application of common sense. However, I am articulating a theoretical framework and subjecting common-sense ideas to rigorous conceptual analysis here. The human (the construction worker) can now, through the mediation of this powerful machine (the digger), dig, scoop and shift a far more significant amount of soil than he could ever have done with only his human body (hands Vs digger bucket). Comparing the two human-world relations, one mediated by technology and one without, warrants the observable, objective conclusion that they are different in orders of magnitude. And that is just from a third-person/party perspective. Imagine this from the first-person perspective. It’s an embodied superpower! It changes the human, it changes the(ir) world, and a new lifeworld emerges.
(Human – Technology → World)
(H—T→W)
Construction Worker — Digger → Elevated, Powerful, Accessible Works-site
This is a typical Ihdean formulaic expression to capture the relations that are made to exist through the technological artefact. I get it, technology mediates the human as they apply intentionality in which case their world.