Pervasive and ubiquitous computing

Teresa Dillon, Futurelab (Web Articles)

“The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it.”

These words were written by Mark Weiser, the ‘godfather’ of ubiquitous computing, in 1991. At the time, Weiser and his colleagues at the Palo Alto Research Centre (PARC) were searching for a term to describe their vision of an embedded computing world. Within this world computers would be an invisible part of our everyday lives. Ahead of their time, Weiser and colleagues used the terms ‘ubiquitous‘ and ‘pervasive‘ computing interchangeably to describe how computing was going to change from desktop, personal computing to a more distributed, mobile and embedded form.

Since the early 1990s other terms have been used to describe this vision, such as ‘calm technology’, ‘transparent technology’ and ‘invisible computing’. Alan Kay, computer scientist and innovator, collectively refers to this as the ‘third paradigm’ of computing, in that technology will become an unseen part of our lives.

But what do the terms pervasive and ubiquitous actually mean? Despite being used interchangeably, they do refer to different forms of computing. One very simple way of discussing the difference is by looking at their dictionary definitions. Ubiquitous means “the state of being everywhere”, while pervasive means to “pass through, to be diffused throughout” (these definitions are taken from the Concise English Dictionary, 1984).

Relating these definitions to ‘real-world’ computing applications, ubiquitous computing is best considered as the underlying framework, the embedded systems, networks and displays which are invisible and everywhere, allowing us to ‘plug-and-play’ devices and tools. Such systems are so embedded and natural that we use them without thinking – except of course when they break down!

Pervasive computing, on the other hand, would be all the physical parts of your life; your mobile phone, hand-held computer or your smart jacket, which changes with your body temperature. Pervasive computing therefore refers to the distributed set of tools within our environment, through which we access information anytime, anywhere.

Currently we are at a more advanced stage in pervasive computing than ubiquitous computing. For example, there are an increasing number of pervasive devices available to the person on the street – mobile phones with web, global positioning systems (GPS) and texting capabilities, PDAs, palm-tops and other hand-held devices are key examples of such technology. Future visions within this area are focusing on the use of tangible and haptic interfaces; such interfaces aim to move away from keyboard and button pressing, to more gestural, tactile and direct sensing interfaces.

In previous Futurelab articles (see references below) we discussed contemporary ubiquitous computing research, such as speckled computing, wireless sensing networks and research in motes, nodes and distributed networks. This research painted a picture of leading edge innovations such as small computing devices (ie the size of matchstick heads), with specific sensing abilities. Examples of work in this area demonstrated how such devices were embedded in buildings and used to continually monitor and adjust the temperature according to the number of people present, time of year and so forth. Much of the research in this field is still at an early stage, and although much progress has been made, the ‘grand visions’ have yet to be achieved.

To some extent ubiquitous computing is the attempt to reduce the need to have an overabundance of physical pervasive devices. Rather, its ‘grand vision’ is to have intelligence built into the things we already use – bikes, cars, toys, fridges and so forth. We are slowly seeing evidence of this within everyday contexts – cars with inbuilt navigation systems, fridges that tell us when we are out of milk or that our food has defrosted.

As a result ubiquitous and pervasive computing are two sides of the same coin. Where ubiquitous computing would require information everywhere, pervasive computing would make information available everywhere. Consequently they share some of the same key goals – the need for useable interfaces, connected via sustainable and scalable distributed networks, where the information is reliable, protected and shared. Key areas of research focus on the development of context-aware and adaptive intelligent systems, devices and networks, which are user-friendly, heterogeneous, flexible and secure.

If the ‘grand visions’ of ubiquitous and pervasive computing happen, we will live in Matrix-like worlds, where dynamic, ad hoc systems will lead to potentially unimaginable efficiencies and possibilities. In journeying towards this brave new world, we need to ensure that not only are the countries currently leading this field benefiting from such innovation but that so called ‘developing’ nations are key partners in this vision. One way to achieve this is through learning and education, not only in developing applications but informing people of the ethical, political and social implications of such worlds.


Dillon, T Wireless Sensing Networks: a US perspective
Satyanarayanan, M Pervasive Computing: Vision and Challenges. IEEE Personal Communications, August 2001:
Weiser, M The Computer for the Twenty-First Century. Scientific American, pp94-10, September 1991:
Pervasive Computing Net:
The IEEE Computer Society:
UbiComp: International Conference on Ubiquitous Computing:

Note:  Web resources developed by Futurelab prior to 2011 used to be hosted by NFER, UK but were decommissioned, hence this is a reproduction from the archive.