 What is it that enables us to encounter music in its fullness even though we are always given, at any particular point in time, only some limited aspect of such a phenomenon (the current note I am hearing)? The answer of phenomenology is that it is the transcendental horizon or conditions that make our encounter with the world possible. One could say that the transcendental is the background, or horizon, that makes the meaningful experience of the foreground possible. Yet insofar as such a formulation suggests a background that is somehow separate and ‘behind’ that which appears in the foreground, it would be incorrect. The transcendental horizon is always and immediately already present in the very appearing as such—this is exactly what makes a horizon ‘disappear’ or withdraw from our focal awareness. It is so evident that it simply does not come up as an issue. It is this seemingly ‘forgotten’ constitutive horizon that is the focus of phenomenology. All phenomenological approaches have as their focus a ‘return’ to this vital co-constitutive interplay between the ‘foreground’ and the ‘background’. Thus, all phenomenological studies share at least the underlying view that technology and society co-constitute each other by being each other’s reciprocal and ongoing condition or possibility for being what they are. As such they continually draw on each other for their ongoing sense or meaning. For the purposes of this entry it might be best to indicate some of the existing phenomenological studies of technology in four different but intimately connected strands (this is not a comprehensive list, it is rather indicative of common themes or approaches):