Short answers, pulled from the story.
Communication is commonly defined as the transmission of information, where a message travels from a sender to a receiver through a medium such as sound, written signs, bodily movements, or electricity. Its precise definition is disputed, with disagreement over whether unintentional or failed transmissions count and whether communication also creates meaning rather than merely transmitting it.
Verbal communication is the exchange of messages in linguistic form, including speech, writing, and sign language such as American Sign Language and Nicaraguan Sign Language. Non-verbal communication happens without a linguistic system and includes kinesics, proxemics, haptics, paralanguage, chronemics, and physical appearance, conveying information through facial expressions, gestures, touch, and posture.
Models of communication are often grouped into linear transmission, interaction, and transaction models. Linear transmission models include Lasswell's model and the Shannon-Weaver model, Wilbur Schramm built the earliest interaction model with a feedback loop, and Dean Barnlund proposed the first transactional model in 1970, defining communication as the production of meaning rather than the production of messages.
Animal communication takes visual, auditory, tactile, olfactory, and gustatory forms, such as firefly flashes, bat echolocation, and bee dances that point toward flowers. Plants rely heavily on chemistry, releasing volatile organic compounds to warn neighbors of herbivore attacks and using mycorrhizal fungi networks known as the Wood-Wide Web to share alerts.
Communicative competence is the ability to communicate effectively and to choose appropriate behavior in a given situation, covering what to say, when to say it, and how. Its two central components are effectiveness, the degree to which a speaker reaches desired outcomes, and appropriateness, which Brian H. Spitzberg defines as the perceived legitimacy or acceptability of behavior in a given context.
Human communication evolved from grunts, cries, and gestures to spoken language, estimated by some to have developed around 40,000 years ago. Writing followed the rise of agriculture, with pictograms around 9000 BCE and Sumerian cuneiform around 3500 BCE, and later milestones included Johann Gutenberg's mass printing in the 15th century, telegraphs, telephones, radio, television, and the internet.