An endangered language is a language that is at risk of falling out of use as its speakers die out or shift to speaking another language. Language loss occurs when the language has no more native speakers and becomes a "dead language". If eventually no one speaks the language at all, it becomes an "extinct language". A dead language may still be observed and studied through recordings or written text, but it is still dead or extinct unless there are fluent speakers. Although languages have always become extinct throughout human history, they are currently disappearing at an accelerated rate by the processes of globalization and neocolonialism, and the economically powerful languages dominate other languages.
More-commonly spoken languages dominate the less-commonly spoken languages and so the latter eventually disappear. The total number of languages in the world is not known. Estimates vary depending on many factors. The general consensus is that there are between 6000 and 7000 languages currently spoken, and that between 50 and 90% of them will have become extinct by 2100. The 20 most common languages, spoken by more than 50 million speakers each, are spoken by 50% of the world's population, but many of the other languages are spoken by small communities, most of them with fewer than 10,000 speakers.
To recognize an endangered languages, the stages of language extinction follow five steps. The first step is potential endangerment. This is when a language faces endangerment, but there are still a few speakers who are keeping the language current and alive. The second stage is endangerment. Once a language has reached the endangerment stage, there are only a few speakers left, risking the chances of the language surviving much longer. The third stage of language extinction is seriously endangered. During this stage, a language is unlikely to survive another generation and will soon be extinct. The fourth stage is moribund, followed by the fifth stage extinction.
UNESCO operates with four levels of language endangerment beyond "safe" (not endangered), based on intergenerational transfer: "vulnerable" (not spoken by children outside the home), "definitely endangered" (children not speaking), "severely endangered" (only spoken by the oldest generations), and "critically endangered" (spoken by few members of the oldest generation, often semi-speakers). Using an alternative scheme of classification, linguist Michael E. Krauss defines languages as "safe" if it is considered that children will probably be speaking them in 100 years; "endangered" if children will probably not be speaking them in 100 years (approximately 60–80% of languages fall into this category) and "moribund" if children are not speaking them now.