Abbr Tag

The <abbr> tag defines an abbreviation or an acronym, like "Mr.", "Dec.", "ASAP", "ATM". An abbreviation and an acronym are both shortened versions of something else. Both are often represented as a series of letters. Marking up abbreviations can give useful information to browsers, translation systems and search-engines.


The set of properties that allows a product, service, or facility to be used by people with a wide range of capabilities, either directly or in conjunction with assistive technologies. Although the term "accessibility" typically addresses users who have a disability, the concept is not limited to disability issues.


"Animation" refers to content that, when rendered, creates a visual movement effect automatically (i.e., without manual user interaction). This definition of animation includes video and animated images.


ARIA stands for "Accessible Rich Internet Applications." ARIA defines ways to make Web content and Web applications (especially those developed with Ajax and JavaScript) more accessible to people with disabilities. For example, ARIA enables accessible navigation landmarks, JavaScript widgets, form hints and error messages, live content updates, and more.

ARIA Label

ARIA is an acronym that stands for "Accessible Rich Internet Applications." An ARIA label is an attribute designed to help assistive technology (e.g. screen readers) provide an accessible name to HTML elements.

Assistive Technology

Assistive technologies that are important in the context of this website include the following:

- screen magnifiers, which are used by people with visual disabilities to enlarge and change colors on the screen to improve the visual readability of rendered text and images.
- screen magnifiers, which are used by people with visual disabilities to enlarge and change colors on the screen to improve the visual readability of rendered text and images.
- screen readers, which are used by people who are blind or have reading disabilities to read textual information through synthesized speech or braille displays.
- voice recognition software, which may be used by people who have some physical disabilities.
- alternative keyboards, which are used by people with certain physical disabilities to simulate the keyboard.
- alternative pointing devices, which are used by people with certain physical disabilities to simulate mouse pointing and button activations.


A distinct characteristic of an object. An object's attributes are said to describe the object. Objects' attributes are often specified in terms of their physical traits, such as size, shape, weight, and color, etc., for real-world objects. Objects in cyberspace might have attributes describing size, type of encoding, network address, etc. Salient attributes of an object is decided by the beholder.


Blindness involves a substantial, uncorrectable loss of vision in both eyes.

Caption Tag

In HTML, the <caption> tag defines a table caption. The <caption> tag must be inserted immediately after the <table> tag. Note: You can specify only one caption per table. By default, a table caption will be center-aligned above a table. However, the CSS properties text-align and caption-side can be used to align and place the caption.


Captions are text transcripts synchronized with other audio tracks or visual tracks. Captions convey information about spoken words and non-spoken sounds such as sound effects. They benefit people who are deaf or hard-of-hearing, and anyone who cannot hear the audio (e.g., someone in a noisy environment). Captions are generally rendered graphically superimposed ("on top of") the synchronized visual track.

Note: Other terms that include the word "caption" may have different meanings in this website. For instance, a "table caption" is a title for the table, often positioned graphically above or below the table.

Color Blindness

Color blindness is a lack of sensitivity to certain colors. Common forms of color blindness include difficulty distinguishing between red and green, or confusing blue with green and yellow with violet. Sometimes color blindness results in the inability to perceive any color.


"CSS" is an acronym for "Cascading Style Sheets." In HTML, cascading style sheets describe how documents are presented on screens, in print, and even in spoken voice. Style sheets allow the user to change the appearance of hundreds of Web pages by changing just one file. A style sheet is made up of rules that tell a browser how to present a document. Numerous properties may be defined for an element; each property is given a value.


An "element" is any identifiable object within a document, for example, a character, word, image, paragraph or spreadsheet cell. In HTML 4.01 and XML, an element refers to a pair of tags and their content, or an "empty" tag - one that requires no closing tag or content.

Em Tag

In HTML, the <em> tag is a phrase tag. It renders as emphasized text. Tip: This tag is not deprecated, but it is possible to achieve richer effect with CSS.

Fieldset Tag

In HTML, the <fieldset> tag is used to group related elements in a form. It draws a box around the related elements.


In online interactions, the "focus" designates the active element (e.g., link, form control, element with associated scripts, etc.) in a view that will react when the user next interacts with the document.

H1 to H6 Tags

The <h1> to <h6> tags are used to define HTML headings. <h1> defines the most important heading and generally appears in a larger size font, while <h6> defines the least important heading.


An impairment refers to an abnormality of body structure, appearance, organ and system functioning. Impairments are problems in body function or structure such as a significant deviation or loss.


The <label> tag defines a label for an <input> element. The <label> element does not render as anything special for the user. However, it provides a usability improvement for mouse users, because if the user clicks on the text within the <label> element, it toggles the control. The for attribute of the <label> tag should be equal to the id attribute of the related element to bind them together.


A placeholder is content generated by the user agent (usually a screen reader) to replace author-supplied content. A placeholder may be generated as the result of a user preference (e.g., to not render images) or as repair content (e.g., when an image cannot be found). Placeholders can be any type of content, including text, images, and audio cues.


The study of relationships between signs and symbols and what they represent. The meaning of a string in some language, as opposed to syntax which describes how symbols may be combined independent of their meaning.

Tabular Information

When tables are used to represent logical relationships among data -- text, numbers, images, etc., that information is called "tabular information" and the tables are called "data tables". The relationships expressed by a table may be rendered visually (usually on a two-dimensional grid), aurally (often preceding cells with header information), or in other formats.


A "transcript" is a text representation of sounds in an audio clip or an auditory track of a multimedia presentation. A "collated text transcript" for a video combines (collates) caption text with text descriptions of video information (descriptions of the actions, body language, graphics, and scene changes of the visual track). Collated text transcripts are essential for individuals who are deaf-blind and rely on braille for access to movies and other content. 

User Agent

A program whose purpose is to mediate interactions with services on behalf of the user under the user's preferences. A user may have more than one user agent, and agents need not reside on the user's desktop, but any agent must be controlled by and act on behalf of only the user. The trust relationship between a user and his or her agent may be governed by constraints outside of P3P. For instance, an agent may be trusted as a part of the user's operating system or Web client, or as a part of the terms and conditions of an ISP or privacy proxy.

WCAG 2.0

Web Content Accessibility Guidelines 2.0 covers a wide range of recommendations for making Web content more accessible.