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Web accessibility refers to the inclusive practice of removing barriers that prevent interaction with, or access to websites, by people with disabilities. When sites are correctly designed, developed and edited, all users have equal access to information and functionality. For example, when a site is coded with semantically meaningful HTML, with textual equivalents provided for images and with links named meaningfully, this helps blind users using text-to-speech software and/or text-to-Braille hardware. When text and images are large and/or enlargeable, it is easier for users with poor sight to read and understand the content. When links are underlined (or otherwise differentiated) as well as colored, this ensures that color blind users will be able to notice them. When clickable links and areas are large, this helps users who cannot control a mouse with precision. When pages are coded so that users can navigate by means of the keyboard alone, or a single switch access device alone, this helps users who cannot use a mouse or even a standard keyboard. When videos are closed captioned or a sign language version is available, deaf and hard-of-hearing users can understand the video. When flashing effects are avoided or made optional, users prone to seizures caused by these effects are not put at risk. And when content is written in plain language and illustrated with instructional diagrams and animations, users with dyslexia and learning difficulties are better able to understand the content. When sites are correctly built and maintained, all of these users can be accommodated without decreasing the usability of the site for non-disabled users. The needs that Web accessibility aims to address include: * Visual: Visual impairments including blindness, various common types of low vision and poor eyesight, various types of color blindness; * Motor/mobility: e.g. difficulty or inability to use the hands, including tremors, muscle slowness, loss of fine muscle control, etc., due to conditions such as Parkinson's Disease, muscular dystrophy, cerebral palsy, stroke; * Auditory: Deafness or hearing impairments, including individuals who are hard of hearing; * Seizures: Photo epileptic seizures caused by visual strobe or flashing effects. * Cognitive/Intellectual: Developmental disabilities, learning disabilities (dyslexia, dyscalculia, etc.), and cognitive disabilities of various origins, affecting memory, attention, developmental "maturity," problem-solving and logic skills, etc. ==Assistive technologies used for web browsing== Individuals living with a disability use assistive technologies such as the following to enable and assist web browsing: * Screen reader software, which can read out, using synthesized speech, either selected elements of what is being displayed on the monitor (helpful for users with reading or learning difficulties), or which can read out everything that is happening on the computer (used by blind and vision impaired users). * Braille terminals, consisting of a refreshable braille display which renders text as braille characters (usually by means of raising pegs through holes in a flat surface) and either a mainstream keyboard or a braille keyboard. * Screen magnification software, which enlarges what is displayed on the computer monitor, making it easier to read for vision impaired users. * Speech recognition software that can accept spoken commands to the computer, or turn dictation into grammatically correct text - useful for those who have difficulty using a mouse or a keyboard. * Keyboard overlays, which can make typing easier and more accurate for those who have motor control difficulties. * Access to subtitled or sign language videos on the Internet for all deaf people. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Web accessibility」の詳細全文を読む スポンサード リンク
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