Short answers, pulled from the story.
Language death occurs when a language loses its last native speaker. Language extinction is when the language is no longer known by anyone, including second-language speakers, at which point it is called an extinct language. A related term is linguicide, the forced death of a language.
As of the 2000s, roughly 7,000 natively spoken languages existed worldwide, most of them minor languages in danger of extinction. The United Nations estimates that a language is lost every two weeks. One 2004 estimate expected some 90% of currently spoken languages to be extinct by 2050.
The main types are gradual language death, radical language death, bottom-to-top death, top-to-bottom death, linguicide, and language suicide. Gradual death is the most common, happening as a community becomes bilingual and proficiency falls across generations. Radical death is sudden, when all speakers cease using a language due to threats, pressure, persecution, or colonisation.
Language death has been linked to physical and mental health in Indigenous communities. One Canadian study found suicide rates six times higher in aboriginal groups where fewer than half of members speak the ancestral language. A study in Alberta, Canada found that greater traditional language knowledge corresponded to lower diabetes prevalence.
The revival of the Hebrew language in Israel is the only example of a language acquiring new first-language speakers after becoming extinct in everyday use. Other revitalization efforts with some success include Welsh, Basque, Hawaiian, and Navajo.
Language death involves the loss of native speakers, while a language such as Latin became a dead language through normal change, analogous to pseudoextinction. Latin evolved through Vulgar Latin into the Romance languages such as French, Portuguese, Spanish, and Italian, with an unbroken chain of transmission, so there is no point at which it died.
Anthropologist Akira Yamamoto identified nine factors, including a dominant culture that favors linguistic diversity, a strong ethnic identity in the endangered community, bilingual and bicultural school programs, teacher training for native speakers, easy-to-use materials, and using the language in new environments. Google also launched the Endangered Languages Project to gather information and research about endangered languages.