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Index	Terminology and Concepts	Definitions	Top
1	1CIF :	See CIF.
2	2CIF :	The same number of lines as CIF, but twice the numbers of pixels per line (i.e. 288 lines and 704 pixels per line).
A	Acceptable price :	The price that end-users are willing to pay for a particular communication service or for improved quality of service. The price of telephony (equipment as well as service) should be used as a benchmark when asking (potential) end-users about acceptable price; and the latter should be expressed as a percentage of the price of telephony, e.g. 50% (half the price of telephony), 300% (three times the price of telephony), etc.
A	Acquaintance relationship task :	This is a task where the primary goal is to communicate, and not to perform a particular task. The roles in the communication are symmetric, i.e. both parties are equal in the communication.
A	Asymmetric [communication or role] :	When the parties in communication are more unequal with respect to expertise or control of the interaction.
A	Audio delay :	Delay of the audio part of the communication signal. See also video delay, audio-video asynchrony.
A	Audio-video asynchrony :	When there is a delay between the audio and the video part of the signal, resulting for instance in the user hearing what is being said before seeing the corresponding lip-movements. See also video delay.
B	Backchannel (verbal) :	Verbal backchannels are any verbalisations from a listener that indicate to the current speaker that the listener understands and that the speaker may continue with his or her turn. Therefore backchannels may be words and/or non-words such as uh-huh, mhm, yeah, OK, sure, etc. They are the verbal equivalents of nodding one’s head.
B	Backchannel (visual) :	Visual (non-verbal) backchannels are mainly head-nods.
B	Benefits :	Benefits to the end-users from using a particular communication service (e.g. savings of travel time and costs, achievement of task goals, ease of use, easy accessibility to the called party, increased communication quality and effectiveness, etc.).
C	CIF :	Common Intermediate Format – a video format defined by ITU-T, where each video frame contains 288 lines and 352 pixels per line.
C	Communication activity :	What the end-users (want to) do with a communication service (e.g. social chatting, buying or selling shares, conducting a job interview, etc.).
C	Communication media :	Types of information with which humans communicate. Examples are text, audio and moving image.
C	Communication service :	A service that is provided via a telecommunication network. Examples are ordinary telephony, email, desktop videoconferencing, studio videoconferencing, avatar-phone, audio-conferencing.
C	Communication situation :	The combination of task, motive, content and user (group) characteristics.
C	Communicative behaviour :	End-user behaviour while using a communication service, including turn taking, interruptions, verbal and non-verbal back-channels and gaze.
C	Communication quality	In the Vis-�-vis context this refers to the subjective impression of the communication quality. The communication quality is affected by factors like audio-video synchrony, delay, resolution, image jerkiness and sound quality.
C	Costs :	Costs that the end-user has to pay for using a particular communication service. These include not only financial costs but also subjective costs; e.g. the user may see loss of privacy as one of the costs to pay for having a videophone.
D	Delay :	Perception of general delay in the communication signal.
D	Duplex :	A mode of operation by which information can be transmitted in both directions simultaneously between two points.
D	Dyadic :	(Distance) communication between two people.
E	Effectiveness (ISO 9241 definition) :	The accuracy and completeness with which specified users can achieve specified goals in particular environments.
E	Efficiency (ISO 9241 definition):	The resources expended in relation to the accuracy and completeness of goals achieved.
E	End-users :	The people who use a communication service for person-to-person communication.
E	End-users :	The people who use the communication service(s).
E	Extrinsic [communication goal] :	When a communication goal has an objective and observable outcome and the goals of the participants involve performing a joint task.
F	Fitness-for-Purpose:	The correct balance between technological performance and human performance, such that the interaction is both sufficient and beneficial for person-person communication and consistent with human expectations from face-to-face communication.
F	fps :	(Video) frames per second
F	Frame rate :	The frequency by which a full video frame is updated, sometimes called video temporal resolution or image frequency.
G	Gaze :	Gazing is whenever a user is looking straight out at the screen.
G	Group :	(Distance) communication between three or more people.
H	Half-duplex:	A mode of operation where, at a given instance, only one of the two correspondent information streams is transmitted.
I	Image jerkiness :	Effect that causes the movements of elements in an image to appear "choppy", or "jerky".
I	Interpersonal perception :	The extent to which the perception of the other person's attributes (how likeable, intelligent, friendly etc.) is positive or negative.
I	Instruction task :	This is a task where the primary goal is to perform a task. The roles in the communication tend to be asymmetric, i.e. the communication may be more one-way and unequal with respect to expertise.
I	Interruption :	If speaker A is speaking and speaker B starts speaking at the same time, then this is defined as an interruption.
I	Intrinsic [communication goal] :	When a communication goal is subjective and personally experienced, with the participants communicating for its own sake rather than to achieve some objective task.
I	ITU :	International Telecommunication Union
J	Joint problem solving task :	This is a task where the primary goal is to perform a task. The roles in the communication tend to be symmetric, i.e. the communication is more symmetric and equal with respect to expertise.
M	Media effects :	The effect a particular communication medium has on an end-users task outcome, communicative behaviour, attitudes and beliefs.
M	Media preferences :	The subjective assessment by users or user groups of when a given communication medium is preferred over another.
M	ms :	milliseconds
M	Multi-point :	Distance communication between three or more locations (also termed Multi-party).
P	PAL :	Phase Alternating Line – a TV standard used in most European countries (except France)
P	Point-to-Point :	Distance communication between two locations
Q	Quality of service :	Those aspects of the service which are assumed to affect the degree of satisfaction of the user of the service (e.g. the number of frames per second in videoconferencing, the auditory bandwidth in audio conferencing).
S	Satisfaction and efficiency :	This refers to the he subjective rating of the user’s satisfaction and feeling of efficiency when using the system. The factors that were rated by the users were: whether the users feel that they communicated well; whether they managed to convey the information they wanted; whether they had the impression that their communication partners managed to convey the information they wanted well; the difficulty of the task; how well they understood the information; whether videotelephony was an appropriate technology for the task; whether it would be easier to perform the task face-to-face; how far they were to prepared to travel to have a physical meeting instead of a videotelephony meeting.
S	Satisfaction (ISO 9241 definition):	The comfort and acceptability of the work system to its users and other people affected by its use.
S	Symmetric [communication or role] :	When the parties in communication are more equal with respect to expertise and interaction.
T	Target audience :	The people or organisations who are going to use the fitness-for-purpose guidelines, the cost-benefit analysis tool and/or the fitness-for-purpose evaluation toolkit.
T	Task efficiency :	Ratings by the user of how difficult the task was to perform.
T	Task elements :	Features of tasks that can be expected to vary (e.g., extrinsic-intrinsic origin, symmetrical-asymmetrical balance, originator-recipient role, ego involvement level, information dependency, sociability level).
T	Task goal :	The aim or object towards which the communication is directed. It is what end-users want to do with the communication technology (e.g. social chatting, buying or selling shares, conducting a job interview, etc.).
T	Task outcome :	The extent to which task performance dependent on the medium.
T	Task :	What users of communicative technology actually do in order to accomplish some task goal. In experiments tasks may be described to the participants or they are embedded in scenarios as a part of a situation.
T	Turn :	A turn is defined as a continuous episode of speech by one person, whether interrupted or not. The start and end of a turn is defined by the start and end of floor holding (or an attempt to gain the floor) by an individual.
U	Usability (ISO 9241 definition) :	The effectiveness, efficiency, and satisfaction with which specified users achieve specified goals in particular environments.
U	User groups :	End-users who with respect to their usage of communication service may be grouped together (e.g. business executives, university students, grandparents, deaf people, etc.).
V	Video delay :	Delay of the video part of of the communication signal. The audio may be synchronous or asynchronous. See also audio delay, audio-video asynchrony.
V	Video resolution :	Resolution of the video image, is sometimes called (video) spatial resolution or picture resolution.
V	VMC :	Video mediated communication
W	Willingness to pay :	An end-users willingness to pay in financial terms for a given communication service in a given situation.