List of languages by total number of speakers

Background

• First, it is difficult to define exactly what constitutes a language as opposed to a dialect. For example, some languages, including Chinese and Arabic, cover several mutually unintelligible varieties and are sometimes considered single languages and sometimes language families. Conversely, colloquial registers of Hindi and Urdu are almost completely mutually intelligible, so they are sometimes classified as one language, Hindustani, instead of two separate languages.
• Second, there is no single criterion for how much knowledge is sufficient to be counted as a second-language speaker. For example, English has about 400 million native speakers but, depending on the criterion chosen, can be said to have as many as 2 billion speakers.

  ''Ethnologue'' (2019, 23rd edition)