Short answers, pulled from the story.
Linguistics is the scientific study of language. Its areas of analysis include syntax, the rules governing sentence structure, semantics, which is meaning, morphology, the structure of words, phonetics, which covers speech sounds, phonology, the abstract sound system, and pragmatics, how context contributes to meaning.
The term linguistics is first attested in 1847 and is now the usual English term for the scientific study of language. The word linguist, meaning a student of language, dates from 1641, while the older term philology was first attested in 1716.
Pāṇini, the 6th-century BC Indian grammarian, undertook an early formal study of language and formulated 3,959 rules of Sanskrit morphology. His classification of Sanskrit sounds into consonants and vowels and of word classes such as nouns and verbs was the first known instance of its kind.
Most contemporary linguists treat spoken and signed data as more fundamental because speech appears universal to humans who can produce it, while many communities have lacked writing. Speech also evolved before writing was invented, and individuals learn to speak earlier and more easily than they learn to write.
A common estimate is 6-7,000 word families to understand a wide range of conversations and 8-9,000 word families to read a wide range of written texts. There is general consensus that reading comprehension of a written English text requires 98% coverage of its words.
Many governments use linguistic analysis, a sub-discipline of applied linguistics, to verify the claimed nationality of asylum seekers who lack documentation. The interview is conducted in the asylum seeker's native language in Australia and in a lingua franca like English in Germany, and the findings can play a critical role in the refugee status decision.
Descriptive linguistics describes and explains features of language without judging whether a usage is good or bad, much as a zoologist studies animals without ranking species. Prescription instead promotes particular usages over others, often to establish a linguistic standard, though it may be practised appropriately in language instruction such as ELT.