“Accessibility is ... a slippery notion ... One of those common terms that everyone uses until faced with the problem of defining and measuring it.” 
This phrase by Gould has been cited on numerous occasions because it sums up so well the complexity of the concept. Accessibility is a relative and contextual notion and the appropriate definition depends largely on the scope and context of the investigation. According to Scott, it is a concept, perception even, that each of us experiences, evaluates and judges differently. 
From universal access to accessibility for persons with disabilities: a single set ofissues
The term “accessibility”, like the term “access” with which it is often confused, has become one of those “portmanteau” words used indiscriminately in varied circumstances and which are often used to hide certain realities rather than shed light on them. Referring in this manner to access or accessibility of education, health and information, as is increasingly fashionable in the “politically correct” stock phrases of international conventions, is a way of relegating the fundamental rights (to education, health, information, and so on) to a secondary role and emphasising only techniques for their distribution and practice. Nevertheless, for persons with disabilities, accessibility has always been a major challenge, as evidenced by the fights led by the community representatives for more than 50 years now. The digital age and the pace of technological development have also brought with them their share of challenges as well as opening up new opportunities for this group of people. It is important to acknowledge the major contribution made by the community to developing concept of accessibility. It is this perspective and the whole set of problems surrounding the full-fledged inclusion of persons with disabilities in the society of shared knowledge that constitute the main theme of this paper.
Accessibility, a condition for universal access for all
At the outset, in order to understand what is at stake as regards accessibility, a definition of what is understood by “universal access” is required. In the field of information technology, it refers to the notions of interoperability, compatibility, equipment, infrastructure... and accessibility. Universal access depends then on the achievement of certain conditions. The World Wide Web Consortium (W3C) defines the notion of universal access as being the possibility for all individuals to access resources on the Web regardless of their hardware, software, language, culture, geographic location, or physical or mental capacities. 
Of the various conditions for universal access, accessibility is probably the one that is the most liable to cause confusion, as everybody promotes it according to the interests and needs of their own community. So, for some communities, accessibility refers to connectivity, while for others it refers to economic resources, infrastructure, cognitive means and education, availability of information and also the degree of “usability” of resources by a person with a disability.
While at first accessibility was, in traditional terms, the facility with which one acceded to and interacted with the physical environment, the advent of the information society has seen the concept of accessibility evolve in order to accommodate the new situation. According to Kwan, the nature of access to opportunities differs radically from that in the physical world, because in cyberspace, interaction among individuals depends more on the availability of communication resources than on the time and cost needed to overcome ¬physical separation . At the heart of the many changes underway is the increasing dissociation between places and functions, as activities are becoming person-based rather than place-based: accessibility in cyberspace is a challenge without a territory.
In addition, the notion of “information accessibility” proposed by Dodge is based on access to relevant resources in a timely fashion. This concern stems from the idea that the Internet can provide access to a vast array of information resources but, precisely because of this information overload, it does not necessarily provide access to useful, current, reliable and affordable information at the right time. 
The debate has been taken further with the assertion that information, social and cultural dimensions should be added to the definition, as the traditional approach to accessibility fails to acknowledge the involvement of individuals in social networks through which information is exchanged, networks which give shape to norms and values on which in turn, to a great extent, accessibility depends.
Recently, it has been possible to observe the impact of certain emerging technologies on accessibility, such as Wi-Fi and the Semantic Web. Wi-Fi now makes it possible to connect to the vast network that is the Web using wireless technology and it is considered to be a major solution in meeting the connectivity needs of certain environments lacking the requisite infrastructure (such as rural areas, developing countries and countries in transition). As to the Semantic Web, although the technology is not yet sufficiently developed or widespread for its implications to be assessed accurately, it aims to improve information accessibility enabling, among other things, concerns to be addressed over access to relevant and reliable information.
Accessibility, an essential condition for access for persons with disabilities
The transformations caused by the development of the information and communication technologies (ICTs) have also had repercussions in the community of persons with disabilities.
Traditionally, for a person with a disability, accessibility has meant that a physical area is designed so that he or she may enter and move about without obstacles, that the facilities, equipment and communications tools have been conceived to permit their use with or without adaptation, by a person having motor, sensory or cognitive limitations . This accessibility is based on the development and adoption of standards and its effectiveness also depends on the moment of implementation (that is, the earlier it is taken into account in the process - construction of a building or a website - , the better).
This need for adaptation is also relevant in a technological context. Several definitions have been proposed regarding accessibility to technology for persons with disabilities. For the United Nations, it means flexible applications that can accommodate each user’s needs and preferences . For the W3C Web Accessibility Initiative (WAI), it means content that is accessible when it may be used by a person with a disability . According to Thatcher and al., when we talk about websites accessibility, the issue of concern is having access to and being able to use web content, whatever the interface or means of connection used .
Essentially, in the disabled community, accessibility to ICTs means that this technology (websites, software, computer hardware, telephony, information stands, automated service machines, etc.) is usable by persons with disabilities, regardless of their impairment or the means of adaptation used .
Technology has always played a major role in fostering the development of the autonomy of persons with disabilities: assistance in communication or mobility, assistance from computers and domotics and, more recently, innovations enabling them to plan their movements with GPS technology. A vast field of expertise in favour of access for persons with disabilities to these technologies has gradually become established around two main themes: the development of technological solutions on the one hand, and information, awareness-raising and political lobbying on the other. The implications of accessibility of technology and content to persons with disabilities or limited mobility are increasingly being taken into account in some societies, with several countries having passed laws in the past ¬¬15 years and signing up to norms to ensure that persons with disabilities can fully play their role of cyber-citizen. The United States, Australia, and the United Kingdom passed legislation several years ago and have now been followed by France, which has passed a law containing obligations regarding the accessibility of public websites. Other countries, such as Japan, Canada, New Zealand and Italy, have also made efforts in this sense. A list of current laws and policies may be consulted on the W3C Web site. 
However, even in the countries that are most sensitive to these issues, there remain several obstacles yet to overcome, and with respect to access to the information society, certain key aspects are not generally sufficiently taken into consideration, as the scope of accessibility is generally limited to technological infrastructure when there are other essential conditions to ensure access to this emerging society.
Thus, persons with disabilities are among the poorest, the least educated and the most marginalized in all societies. They number more than 600 million throughout the world, 80% of them in developing countries and countries in transition. They have few opportunities to take part in the development of their communities and influence their fate. Although their effective integration in today’s society is taking a long time to secure, the challenges around their integration in tomorrow’s society are considerable, and cannot be confined only to technological considerations.
The three conditions for the development of accessibility
As we have already seen, the demand to take into account social and cultural dimensions in the development of universal access is not new. In this spirit, the work around the World Summit on the Information Society (WSIS) has tried to allow for particular needs, such as education (in the perspective of capacity-building) and access to community resources . The United Nations has done some interesting work in this respect through its World Programme of Action concerning Disabled Persons. It puts forward the notion of “environmental accessibility”, which includes the planning and introduction of measures to promote social integration and full and effective participation by all on the basis of equality. 
In the context of interest to us, we should then see accessibility for persons with disabilities as a fundamental dimension and prerequisite of universal access to the information society. This accessibility must take the form of an inclusive, participatory and standardised approach:
Inclusive, because it takes into account the needs of all in the design, introduction, and evaluation of strategies, policies, programmes, and projects;
Participatory, because it ensures the participation of all in decision-making with an impact on the life of individuals and communities;
Standardized, because it develops and adopts concepts, procedures, and standards that take into account the social, economic, cultural, linguistic, physical, and geographical differences of all.