Glossary A - Yenra

Advanced Audio Distribution Profile: a Bluetooth Classic profile for distributing media audio from a source, such as a phone, to a receiver, such as headphones. Both endpoints need compatible profile and codec support. Hands-free call audio uses a different profile, and playback-control commands are a separate part of the device’s supported functions.

Guide: Bluetooth Audio: Compatibility, Sound Quality, and Troubleshooting

Reference: Bluetooth SIG: Advanced Audio Distribution Profile

Compare: Bluetooth profile, HFP, Codec

An antenna's gain in a specified direction relative to an ideal isotropic radiator, using consistent power and polarization conditions. The reference matters when comparing antenna specifications.

Reference: NTIA: antenna gain and patterns (PDF)

The name a browser determines for an interface element and exposes to assistive technology, helping users identify its purpose. It may come from visible label text, element content or an explicit naming attribute. Check the computed name in context, keep visible wording consistent, and use a separate description for additional instructions when needed.

Guide: Accessibility Evaluation and Repair: From Finding to Retest

Reference: W3C: accessible names and descriptions

Compare: Form label, Screen reader, Semantic HTML

An optical system that measures changing distortions in incoming light and rapidly adjusts a deformable mirror to reduce them. Ground-based telescopes commonly use a reference star or laser-created beacon to sense atmospheric effects near a target. Correction quality depends on observing conditions and the system, so compare corrected images at stated wavelengths and angular scales.

Guide: Laser Guide Stars: How Adaptive Optics Sharpens Telescope Images

Reference: ESO: adaptive optics and guide-star references

Compare: Angular resolution, Diffraction

Advanced Gateway Server, an early Cisco router product. Historical specifications describe the particular hardware generation and should be kept separate from present-day networking requirements.

The time radio transmissions occupy a wireless channel. Data, management traffic and retransmissions all consume this shared resource; sending the same payload at a lower radio rate generally takes longer. When a busy network slows down, examine channel use and retries alongside signal strength and internet capacity to locate the constraint.

Guide: Wi-Fi Channel Planning: Balance Width, Reuse and Airtime

Reference: Cisco Meraki: capacity planning and management-frame airtime

Compare: Channel width, Throughput, RSSI

Ambiguity created when different signal frequencies produce indistinguishable sampled values. With inadequate sampling for the input bandwidth, a changing signal can appear at a false lower frequency. Choosing a suitable sample rate and filtering unwanted higher-frequency input before sampling helps prevent this. Sampling more often also needs a sensor that can follow the underlying change.

Guide: Data Loggers: Plan a Measurement You Can Trust

Reference: NI: sampling, bandwidth and aliasing

Compare: Sample rate, Sensor response time, Interpolation

The Atacama Large Millimeter/submillimeter Array, a radio observatory whose antennas work together to study the universe at millimeter and submillimeter wavelengths. An array's baselines help determine the angular detail it can resolve.

Related coverage: Radio Telescope Antennas: How Arrays Make an Image

A text alternative that conveys an image’s information or purpose in its context. A screen reader can present it to someone who cannot see the image. Informative images need useful equivalent meaning, while purely decorative web images generally use an empty alternative so they do not interrupt reading.

Guide: Astra QuickTest and Accessibility Regression Testing: From Recorded Actions to Useful Checks

Reference: W3C: image text alternatives

Compare: Screen reader, HTML, OCR

Active-matrix organic light-emitting diode: a display arrangement that uses an active matrix to control light-emitting pixels. The display technology name is one part of a screen specification, alongside resolution, brightness and other properties.

Related coverage: HP iPAQ Glisten

Advanced Medium-Range Air-to-Air Missile, the name of the AIM-120 missile family. A useful program description identifies the variant, platform and source date because the family has developed over time.

Related coverage: AMRAAM Explained: AIM-120 Variants, Platforms, and Program History

The smallest angular separation at which an observing system can distinguish nearby features or sources. Astronomers commonly express it in arcseconds; smaller values indicate finer detail. Wavelength and aperture set an ideal diffraction scale, while the atmosphere, optical quality and detector sampling affect delivered images. Magnification enlarges the view without automatically improving this resolving ability.

Guide: Infrared Telescopes: Wavelengths, Thermal Background and What Images Reveal

Reference: NASA: angular resolution, aperture and wavelength (PDF)

Compare: Diffraction, Adaptive optics, Spatial resolution (imagery)

Security software that detects, blocks or removes known or suspicious malicious activity using methods such as signatures and behavioral analysis. Its findings need interpretation, and protection also depends on updates, backups and other controls.

Read the guide: Antivirus Protection: What You Need and How to Check It

Reference: Microsoft: virus and threat protection

Adaptive predictive coding: a signal-coding approach that adjusts its prediction to the signal being encoded. A codec specification is needed to establish the particular algorithm and data format.

American Power Conversion, the company name behind the APC power-protection brand. Compatibility and capability depend on the particular product model; the linked guide explains battery and power-bank checks.

Related coverage: Laptop Batteries and Power Banks: Compatibility, Health, and Runtime

The lens opening through which light passes, commonly described by an f-number. At a given focal length, a lower f-number means a larger opening and more light during the same exposure time. Aperture also affects depth of field; many phones have a fixed physical aperture, even when software simulates background blur.

Guide: Landscape Photography: Plan the Frame, Light, and Exposure

Reference: Nikon: aperture and depth of field

Compare: Depth of field, Shutter speed, ISO (photography)

Access that an operating system grants an application to a protected capability or data, such as the camera, microphone, contacts or location. Available controls depend on the platform and can limit when access is allowed. Match each permission to the task, and review the app’s handling of collected data separately from the device’s permission setting.

Guide: Mobile App Security and Privacy: Review Access Before Adoption

Reference: Google: managing Android application permissions

Compare: Authorization, Least privilege, Mobile device management

Application-specific integrated circuit: a chip designed for a particular set of functions. Networking devices may use ASICs for packet processing and other tasks with defined performance requirements.

Automatic Switching of Network Access Points, a name used in historical dual-network mobile-phone coverage. Read it in that system's context rather than as a universal name for Wi-Fi or cellular handover.

Related coverage: Wi-Fi and Cellular Switching: Calls, Data, and Handoff Tests

The ratio of an image's width to its height, such as 3:2 or 4:3. Printing or displaying it in a different-shaped frame requires cropping, added borders or distortion; pixel dimensions are a separate specification.

Read the guide: CMOS Image Sensors: Size, Pixels, Noise and Shutter Readout

Asynchronous Transfer Mode: a connection-oriented networking technology using fixed 53-byte cells. Virtual connections organize traffic through the network; the acronym here refers to telecommunications rather than a cash machine.

A judgment assigning an artwork to an artist, workshop, school or period. The wording expresses the strength and scope of the claim; assess the supporting research and evidence alongside the label.

Read the guide: How the Art Business Works: People, Records and Provenance

Reference: Getty: creation and attribution

ARC sends audio from a television back to a compatible soundbar or AV receiver over HDMI, including audio from TV apps. Enhanced ARC, or eARC, provides a higher-capacity return path supporting additional audio formats. Check both devices’ supported ports, formats and settings; CEC handles control commands rather than carrying this audio.

Guide: HDMI: Choose the Right Connection and Troubleshoot It

Reference: HDMI: ARC and enhanced ARC

Compare: HDMI, CEC, PCM (audio)

The selection of paths that carry sound from sources to outputs, and microphone input to an application or call. A phone can direct music to a car stereo while a call uses another connected device. When sound is missing or misplaced, check the active input and output at each stage as well as its volume.

Guide: Bluetooth Car Stereo: Setup, Missing Audio, and Upgrade Options

Reference: Google: Bluetooth media and call-audio destinations

Compare: HFP, A2DP, Bluetooth multipoint

Audio data delivered progressively so playback can begin before a complete program has been downloaded. The stream's codec, address, access requirements and delivery reliability affect whether a player can use it.

Read the guide: Internet Radios: Choose a Receiver, Find Stations, and Set It Up

Checking evidence that an entity is who or what it claims to be. A password, security key or certificate may participate in that check; authorization separately determines what the authenticated entity may do.

Read the guide: Web Service Security: Access, XML Parsing, and Resource Limits

Reference: OWASP: web-service security

Compare: Authorization

Deciding whether an entity is permitted to perform an action or access a resource. Enforcing permissions for each relevant request helps keep a valid login from gaining unintended access.

Read the guide: Web Service Security: Access, XML Parsing, and Resource Limits

Reference: OWASP: web-service security

Compare: Authentication

The proportion of a defined period during which a service meets its agreed usable state. A percentage is meaningful only with a measurement period, service boundary and treatment of excluded downtime.

Association of Volleyball Professionals, the professional beach-volleyball organization referred to by this acronym. The sports context distinguishes this use from unrelated business and technical abbreviations.

Related coverage: Beach Volleyball: Rules, Scoring and What to Watch

An audio/video receiver that selects and routes sources, processes audio and usually includes power amplifiers for several speaker channels. It can act as the connection hub for a home theater. Supported formats, inputs, speaker assignments and amplification vary by model, so plan around the actual manual and connected equipment.

Guide: AV Receiver Setup: Inputs, Speakers, and Listening Modes

Reference: Yamaha: the AV receiver as a system hub

Compare: HDMI, Crossover (audio), Speaker impedance

The ratio of a device's output signal to its input signal under specified conditions. State whether the ratio describes power, voltage or another quantity before comparing values.