A version of a document, email, or electronic disc that is in plain text, word processing format, HTML, PDF, or some other format that can be accessed with screen reader software.
Alternatives to print or written documents, or to other visual presentations, such as power points and videos, that are accessible to people who are blind or have low vision.
Devices or systems that increase the volume of a desired sound, such as the soundtrack of a movie or the voice of a tour guide, without increasing the loudness of background noises. Assistive listening systems are made up of two parts: the transmitter (which picks up the sound, converts it to a signal, and sends the signal) and the receiver (or ALD) (which picks up a signal and transmits it to the user). Several receivers can pick up the signal from a signal transmitter. There are several types of assistive listening systems, including infrared and FM systems.
An audio narration of a visual presentation (e.g., on television, on a video tape or DVD, or on the internet) for those who are blind or have low vision. It usually consists of oral descriptions of key visual elements of the presentation, such as settings and actions not reflected in dialog. Narrations are generally inserted into the presentation’s natural pauses.
Devices, services, and other methods used to ensure effective communication with individuals with disabilities. They include interpreters, note-takers, assistive listening devices, captioning, TTYs, readers, Brailled materials, and large print materials.
A series of raised dots that can be read with the fingers by people who are blind or whose eyesight is not sufficient for reading printed material. When every letter of every word is expressed in Braille, it is referred to as Grade 1 Braille. The system used for reproducing most textbooks and publications is known as Grade 2 Braille. In this system, cells are used individually or in combination with others to form a variety of contractions or whole words.
The transcription and subsequent text display of the audio portion of a video presentation, broadcast, or other on-screen presentation, including dialog and other auditory information, such as on- and off-screen sound effects, music, and laughter. Captioning enables people with hearing disabilities to have access to the audio portion of the material but also helps others who may have difficulty understanding or following aural material.

There are two categories of captions:

Video signals hidden within a movie, DVD, TV program, or similar visual presentation, making text visible (usually across the bottom of the screen) when the captioning is turned on through televisions equipped with decoders (all televisions manufactured after July 1, 1993), or other equipment.
Captioning that is encoded as an integral part of a movie, videotape, or TV show and cannot be turned off, similar to subtitles on foreign films.
CART (Communication Access Real-time Translation or Computer Assisted Real Time Transcription)
A word-by-word translation of spoken English onto a laptop or notebook computer by use of real-time software and a steno machine. CART is similar to captioning but displayed on a laptop or screen.
An impairment to attention, orientation, memory, problem solving, judgment, information processing, or behavior. Cognitive disabilities include intellectual disabilities (a type of developmental disability formerly known as “mental retardation”) and certain learning disabilities (such as dyslexia), and can also stem from organic brain syndrome, Alzheimer’s Disease and other dementias, and stroke.
A change or modification to a program that is so significant that it alters the essential nature of the goods, services, facilities, privileges, advantages, or accommodations provided.
Individuals who facilitate communication between people who have disabilities relating to hearing, speech, and/or vision and use sign language, cued speech, or speech-reading and those who do not. Interpreters fall into several categories:
Interpreters who use eight hand shapes in four different locations around the face and neck to represent sounds used in spoken language. Cued Speech is a phonetically based visual communication system. It is not a form of language. It is generally used as an adjunct to speech reading.
Interpreters who mouth a speaker’s words silently, to give higher visibility on the lips, for added comprehension by people who are deaf or hard of hearing and use speech reading. Oral interpreters are skilled at pronouncing words clearly using their lips and may also use facial expressions and gestures. They are also skilled in quickly substituting words which are hard to lip read, while keeping the content and emotion of the speaker’s statement intact.
Interpreters who facilitate communication between people who use sign language and those who do not. When a hearing person speaks, an interpreter will render the speaker's meaning into the type of sign language used by the person who is deaf. When a person who is deaf signs, an interpreter will render the meaning expressed in the signs into the spoken language for the hearing person, which is sometimes referred to as voice interpreting or voicing. This may be performed either as simultaneous or consecutive interpreting.
Interpreters who convey information using various methods, but always in a way that relies on touch, to people who are deaf-blind and generally receive information tactilely, i.e., through touch. Methods employed by tactile interpreters include using sign language (with the person who is deaf-blind resting one or both hands on the interpreter’s hands or wrists), using fingers to trace the letters of words in the palm of the person who is deaf-blind, and using the manual alphabet to spell words into the hand of the person who is deaf-blind.
Printed material enlarged for people with low vision. For large print materials, the size of type required will vary with the needs of the reader and with the font used. Large print items generally use a sans serif font with a minimum font size of 16 to 18 points.
People who take notes for individuals who are deaf or hard of hearing. Note-takers may be needed because people with significant hearing loss must look at speakers or interpreters to understand what is being said. As a result, each time they look down to record a comment, they miss information being presented.
Any mobility device powered by batteries, fuel, or other engines that is used by individuals with mobility disabilities for the purpose of locomotion, including golf cars, electronic personal assistance mobility devices such as a Segway® PT, or any mobility device designed to operate in areas without defined pedestrian routes, but that is not a wheelchair.
A person who assists an individual with a disability (e.g., one who is blind or has a learning disability) by reading printed material in person or recording to audio-tape.
Software that magnifies the displayed page.
Software used to echo text on a computer screen to voice output (through a speech synthesizer), often used by people who are blind, with visual impairments, or with learning disabilities. Screen readers read everything that is on the computer screen out loud so a person can hear what has been typed on the screen. Some screen readers can only read web pages; others can read both web pages and text in a document.
Any dog that is individually trained to do work or perform tasks for the benefit of an individual with a disability, including a physical, sensory, psychiatric, intellectual, or other mental disability. The work or tasks performed by a service animal must be directly related to the handler’s disability.
Manual communication commonly used by deaf persons. The gestures or symbols in sign language are organized in a linguistic way. Each individual gesture is called a sign. Each sign has three distinct parts; the hand shape, the position of the hands, and the movement of the hands. People from different countries use different sign languages. There are several types of sign language used in the United States, including:
ASL is the most commonly used sign language in the United States. It has developed over time through use by people who are deaf and is a free-flowing, natural language. ASL is a language complete in itself. It is not usually written or spoken, but can be translated, just like French or German, to English and vice versa. ASL has its own syntax and grammar. A sign is not executed for every word in a sentence, and the syntax and structure of the communication is not parallel to English.
The vocabulary is drawn from ASL but follows English word order. The language is expanded with words, prefixes, tenses, and endings to give a clear and complete visual presentation of English. With Signed English a sign is executed for every word in a sentence, whereas American Sign Language seeks to convey a concept. For example, to sign “I have two sisters” in Signed English, one would make a sign for each word. In ASL, one might make the signs for “two” and “sister” and then point to herself, conveying the thought “two sisters, me.”
A service that enables persons who use TTYs or other telecommunication devices (generally, people who are deaf or hard of hearing or have speech disabilities) to use telephone services by having a third party transmit and translate the call. Also called RELAY or RELAY SERVICE , TRS is provided at no additional cost and mandated by Title IV of the Americans with Disabilities Act and provides a link between callers who use assistive devices such as TTYs, and callers who do not have or use such equipment. It also serves as an interface between people who have speech disabilities and those who have difficulty understanding them. A Communications Assistant (CA) relays information between the caller and the call recipient.

There are several types of TRS calls:

TTY Calls
People who use a TTY (see below) can use TRS to make calls to people who do not use a TTY. Likewise, callers who use standard telephones can make calls to TTY users. When using the Relay, the TTY user types a message to the CA who then reads it to the person using a standard telephone. When the person using a standard telephone responds, the CA types the message to the TTY user.

Voice Carry Over (VCO)
VCO allows callers who can speak intelligibly but who cannot hear conversations on the telephone (for example, people who are hard of hearing), to speak directly with a person using a standard telephone on the other end of the line. The CA types the standard telephone user’s comments back to the VCO user who reads the text display from a TTY or specially equipped telephone.
Hearing Carry Over (HCO)
HCO allows people who can hear but who cannot speak clearly (for example, people who have had severe strokes) to hear conversations via a standard telephone while using a TTY to type their comments. HCO users type their comments to the CA who reads them to the person using a standard telephone on the other end of the line. The standard telephone user then speaks directly to the HCO user.
Speech to Speech (STS)
STS services are used by people who have speech disabilities and are neither deaf nor hard of hearing (for example, people who have cerebral palsy). With STS, CAs are trained to understand people who have speech disabilities. The CA listens to the caller with a speech disability and then repeats the message in clear speech to the person on the other end of the line.
Spanish Relay Service
Relay calls using TTY, VCO, HCO, and IP Relay must be provided in Spanish for all interstate calls. Spanish Relay is only required for calls where both parties use Spanish; it is not a translation service. Both Spanish Relay users and standard telephone users can initiate and receive Spanish Relay calls.
IP Relay
IP (Internet Protocol) Relay calls can be made using internet enabled computers or other internet devices. The IP Relay user types a message to the CA who reads it to the person using a standard telephone. When the person using a standard telephone responds, the CA types the message back to the IP Relay user.
Video Relay Service (VRS)
VRS allows consumers who use sign language to communicate via the telephone system. VRS callers who use American Sign Language (ASL) must have the appropriate video equipment and high speed connectivity, e.g., cable modem, DSL (Digital Subscriber Line), or ISDN (Integrated Services Digital Network). The sign language user signs to a CA who is also a qualified sign language interpreter. The CA interprets the message into spoken English for the standard telephone user who then responds in spoken English. The CA listens to the spoken message and interprets it into sign language for the signing caller. Video Relay Service is a fairly recent addition to the Relay Service, but it is different from traditional Relay Service in that either a videophone with TV or web camera with computer screen is used. Video Relay Service also differs from traditional relay service in that the Video Interpreter (VI) views the person using sign language. The VI then relays the conversation of the person using sign language to the hearing caller, via voice. The VI then continues to interpret the call between the two, using the phone line/video connection.
A type of machine that allows people with hearing or speech disabilities to communicate over the phone using a keyboard and a viewing screen. “TTY” was originally an acronym for TeleTYpewriter. Today, these devices are sometimes also called TDDs (Telecommunications Devices for Deaf persons) or TTs (Text Telephones), although the preferred term is TTY. TTYs include a keyboard (which is connected to a modem), text display, and sometimes a printer. TTY’s allow individuals to make and receive telephone calls in real time using typed, two-way communication. (Some messages received via TTY are written in non-standard English. This is because English is not a first language for many people who are deaf.) The person using the TTY types on the keyboard and the signal is then transmitted through the phone line to a compatible device: either another TTY/TDD, a computer with a modified modem capable of receiving the signal, or a TELECOMMUNICATIONS RELAY SYSTEM.
Software that produces computer-generated speech, through means such as a keyboard or touch screen/pad, for selecting the words or phrases the user would like the computer to vocalize.
A financial or administrative burden so severe that an entity is relieved of certain otherwise mandated responsibilities. In determining whether an action would result in an undue burden, factors to consider are the nature and cost of the action needed, and whether such action would result in significant difficulty or expense.
A means of using an interpreter (e.g., sign language), who is in a location separate from the participants in a communication. The interpreter appears via video on a computer screen or videophone, through a computer or videophone connection.
A telephone that permits callers to send and receive both audio and video signals. The VP’s ability to provide direct visual contact between callers has made it especially useful for the deaf and hard of hearing communities. Since callers can see each other, deaf and hard of hearing users who prefer to communicate by sign language can do so via telephone and do not need to rely on either text (e.g., TTY) or voice. VP users can also communicate with standard telephone users by using VIDEO RELAY SERVICES (VRS) (see above under TRS).

[1] Compiled, with edits, from the following sources: Glossary of Telecommunication Terms, Federal Communication Commission, http://www.fcc.gov/glossary.HTML (visited October 8, 2013); Section 504 Programs & Activities Accessibility Handbook, 2nd Edition, Federal Communications Commission, http://www.fcc.gov/cgb/dro/section_504.html (visited October 8, 2013); Glossary of Disability-Related Terms, DoIT, University of Washington, http://www.washington.edu/doit/Brochures/Programs/glossary.html (visited October 8, 2013); Disability-Related Glossary of Terms, Indiana Institute on Disability and Community, Indiana University, http://www.iidc.indiana.edu/cedir/glossary.html (visited October 8, 2013); Disability Services in Higher Education Resources, University of Illinois at Chicago, Department of Disability and Human Development, http://www.disabilityresources.uic.edu/ (visited October 8, 2013); DOJ ADA Regulations, 28 CFR Parts 35, 36.