Communication

Diffie–Hellman key exchange Diffie-Hellman key exchange A foundational public-key method for two parties to establish a shared secret over an insecure channel, relying on the difficulty of the discrete logarithm problem.

Digamma (ancient Greek letter) Digamma Digamma, originally called Wau, is an archaic Greek letter shaped like F and pronounced /w/; it later became the numeral 6 (stigma/episemon) and lends its name to the mathematical…

Digital signal A signal that represents information with discrete values or as a sequence of samples; fundamental to digital electronics, communications, computing, and signal processing.

Digital Subscriber Line (DSL): technology, variants, and uses Digital subscriber line Digital Subscriber Line (DSL) transmits digital data over copper telephone lines. This article describes how DSL works, its main variants (ADSL, SDSL, VDSL), deployment history, ty…

Digraph (orthography): two-letter graphemes in writing systems Digraph (orthography) A digraph is a pair of letters used together to represent a single sound or a unit of writing. This article explains types, examples from several languages, history, and distinctio…

Diphthong (phonetics) — complex vowel glides Diphthong A diphthong is a complex vowel sound that glides between two vowel qualities. This article explains its phonetic nature, types, examples in several languages, history of the term,…

Discord (communication platform) Discord Discord is a cross-platform communication app for voice, video and text organized into user-created servers. It began with gamers and expanded to communities, creators, study group…

Discord (software) — a cross‑platform communication platform Discord (software) Discord is a cross-platform communication app for text, voice and video. Originating in gaming, it now hosts wide-ranging communities, servers, bots and optional paid features for…

Discourse analysis Study of language beyond the sentence: how texts and conversations create meaning in social context, including methods, history, applications, and key concepts in linguistics and r…

Disinformation: definition, methods, history and responses Disinformation Deliberately false information spread to deceive. Covers definition, techniques (forged documents, images, rumors), historical echoes, effects on society, and common countermeasure…

Dje (Ђ, ђ) — Serbian Cyrillic letter Dje Dje (Ђ, ђ) is a letter of the Serbian Cyrillic alphabet that denotes the voiced alveolo‑palatal affricate /dʑ/, created by Vuk Karadžić and transliterated as Latin Đ (đ).

Dogri language — an Indo‑Aryan tongue of the Jammu region Dogri language Dogri is an Indo‑Aryan language of the Jammu region, classified with Western Pahari languages. It has its own oral traditions, scripts (Takri, Devanagari), modern literature and of…

Dollar sign ($): appearance, history, and common uses Dollar sign Overview of the dollar/peso sign ($): its shapes, origins, typographic forms, monetary uses for dollars and pesos, computing roles, and distinctions between single- and double-stro…

Domaaki language (Dumaki, Domaá) Domaaki language Domaaki is a highly endangered minority language of northern Pakistan, spoken by the Dóoma people in the Nager and Hunza valleys. Fewer than 350 speakers remain; the language faces…

Dominican Spanish: Features, History, and Social Use Dominican Spanish Variety of Spanish spoken in the Dominican Republic and by its diaspora, notable for Caribbean phonology, Canarian and African influences, Taíno vocabulary, and strong regional and…

Doric dialect (Northeast Scots) Doric dialect (Scotland) Doric is the traditional Scots dialect of northeastern Scotland, spoken across Aberdeenshire, Moray and neighbouring areas; notable for distinctive sounds, vocabulary and strong re…

Dotted and dotless I: the Turkish letters İ and I Dotted and dotless I Two distinct letters in Turkish (İ/i and I/ı) with different sounds and uppercase forms. They affect pronunciation, orthography, computing, and appear in several Turkic languages t…

Dual-Tone Multi-Frequency (DTMF) Signaling: How Telephone Touch-Tones Work Dual-tone multi-frequency Learn how Dual-Tone Multi-Frequency (DTMF) touch-tones use paired low/high audio frequencies to encode keypad presses, how networks decode them, and their role in dialing, IVR, voi…

Dutton Speedwords Dutton's Speedwords A compact constructed writing system by Reginald J. G. Dutton (1886–1970) designed as both an international auxiliary vocabulary and a rapid, typeable shorthand using short Roman-l…

Dynamic and formal equivalence in translation Dynamic and formal equivalence Two contrasting approaches to translation: dynamic (functional, idiomatic) equivalence focuses on sense and effect, while formal (literal) equivalence preserves wording and structu…

Dysphemism: harsh or derogatory language used instead of neutral or polite terms Dysphemism Dysphemism is the deliberate use of a blunt, offensive, or derogatory term in place of a neutral or polite expression; it functions rhetorically in insult, humor, emphasis, or fram…

Dzhe (Cyrillic letter Џ) Dzhe Dzhe (Џ, џ) is a Cyrillic letter representing the voiced postalveolar affricate /dʒ/ (as in English "jump"). It appears in Serbian, Montenegrin, Bosnian (Cyrillic) and Macedonian a…

E Prime: an English usage that omits the verb 'to be' E Prime E Prime (English Prime) is a style that avoids all forms of the verb 'to be' to promote clarity, responsibility, and more precise expression in writing and speech.

E-mail attachment A file sent together with an e-mail message. Attachments let users share documents, images and other data; they are subject to encoding, size limits, security risks and common etiq…

Echolocation: biological sonar used by animals and its technological parallels Echolocation Echolocation is active biological sensing in which animals emit sounds and interpret returning echoes to locate and identify objects; found in bats, toothed whales, some birds and…

Ef (Cyrillic letter Ф, ф) Ef (Cyrillic) Ef (Ф, ф) is the Cyrillic letter representing the voiceless labiodental fricative /f/. It appears in most Cyrillic alphabets and derives from the Greek letter phi.

Egyptian language: history, writing, and legacy Egyptian language Overview of the Egyptian language: classification, chronological stages from Old Egyptian to Coptic, scripts and decipherment, grammar and phonology, liturgical use and influence o…

Ekiga: Free VoIP and Video Conferencing for GNOME and Windows Ekiga Ekiga is a free, open-source softphone and videoconferencing application for GNOME and Windows that supports SIP and H.323 protocols and interoperates with other SIP clients and Mi…

El (Cyrillic letter Л, л) El (Cyrillic) El (Л, л) is the eleventh letter of the Cyrillic alphabet, representing an /l/ sound. It derives from Greek lambda and corresponds to the Latin L; it has distinct printed and cursi…

Electrical telegraph: technology, history, and impact Electrical telegraph The electrical telegraph transmits coded messages over wires using electric current, keys, sounders, relays and batteries. It transformed 19th-century communication, enabling near‑…

Ellipsis (three-dot punctuation) Ellipsis A punctuation mark of three consecutive dots used to indicate omission, pause, trailing thought, or continuation; also appears in mathematics and computing as horizontal or vertica…

Em (Cyrillic letter М, м) Em (Cyrillic) Em (М, м) is the twelfth Cyrillic letter representing the voiced bilabial nasal /m/. It derives from Greek mu and corresponds to the Latin M in sound, transliteration and alphabeti…

Emergency Alert System (United States) Emergency Alert System Overview of the U.S. Emergency Alert System: purpose, operation, message types, history, testing, and how agencies and the public interact with alerts.

Emergency Communication Systems Emergency communication system Overview of emergency communication systems: purpose, components, history, uses, design principles, and common challenges for public safety and disaster response.

Emergency telephone (emergency call box) Emergency telephone A public telephone device that provides one-touch access to help services. Installed in remote, high-risk or high-traffic locations, designed for rapid contact, visibility, and loc…

Emergency telephone number Short, easy-to-remember phone numbers reserved for calling police, medical, fire, or other urgent public services; systems vary by country and now include mobile and location featu…

Emission: release of matter or energy from a source Emission Emission is the release or sending out of matter or energy—gases, particles, light, sound or heat—from natural or human sources; it has scientific, environmental and technological…

Emoji — origins, standards, and cultural impact Emoji Overview of emoji: pictographic characters originating in Japan, standardized by Unicode, used to convey emotion, objects, actions and ideas across devices and languages.

Emoticon: text symbols that convey emotion and tone Emoticon Emoticons are sequences of characters that represent facial expressions or moods in writing. They appear in plain text, chat and forums and are related to kaomoji and emoji, servin…

Endangered language A language at risk of falling out of use because of declining numbers of native speakers, with cultural, social, and linguistic consequences and various revitalization responses.

English language: origins, structure, global spread and varieties English language Overview of the English language: its origins, development, structure, world status, principal varieties, and uses in education, diplomacy, science and everyday life.

English-speaking world: distribution, varieties, history and global role English-speaking world Survey of the English-speaking world: its speakers, major varieties, history of spread, international uses, and notable distinctions between native and second-language contexts.

Envelope (mailing container and document wrapper) Envelope An envelope is a folded paper or similar container used to enclose documents for mailing, storage, or presentation. Types include business, window, manila, padded and security enve…

Er — Cyrillic letter Р (uppercase) and р (lowercase) Er (Cyrillic) Er (Р, р) is a consonant letter of the Cyrillic alphabet representing an r sound. Originates from Greek rho; appears across Slavic and non‑Slavic Cyrillic orthographies and is typi…

Er with tick (Cyrillic letter used in Kildin Sami) Er with tick Er with tick (Ҏ ҏ) is a modified Cyrillic letter used in the Kildin Sami alphabet to represent a distinct rhotic consonant. It appears only in that Sami orthography and in extended…

Error detection and correction Methods and algorithms that detect and often correct errors in stored or transmitted information by adding redundancy and using mathematical checks to ensure data integrity.

Es (Cyrillic letter С, с) Es (Cyrillic) Es (С, с) is a common letter in Cyrillic alphabets representing the voiceless s sound. It traces to Greek sigma and corresponds to the Latin S in pronunciation and transliteration.

Estonian language (Eesti keel) Estonian language A Uralic language spoken primarily in Estonia, related to Finnish, with a unique phonology, several dialects, and official status in Estonia; influenced by Germanic and Slavic lang…