1. Linguists use the term "vernacular" to refer to the everyday language a person grows up with and uses in ordinary social interactions.
2. There is ambiguity around the terms "language" and "dialect" - language typically refers to a single linguistic norm or related norms, while dialect refers to one variation. Different dialects of the same language are not considered different languages.
3. Bell identified 7 criteria for distinguishing a language from others: standardization, vitality, historicity, autonomy, reduction, mixture, and de facto norms. These criteria look at factors like codification, community of speakers, sense of identity, differences from other languages, and perceptions of proper usage.