Code-mixing is the mixing of two or more languages or language varieties in speech. Some scholars use the terms "code-mixing" and "code-switching" interchangeably, especially in studies of syntax, morphology, and other formal aspects of language. Others assume more specific definitions of code-mixing, but these specific definitions may be different in different subfields of linguistics, education theory, communications etc. Code-mixing is similar to the use or creation of pidgins, but while a pidgin is created across groups that do not share a common language, code-mixing may occur within a multilingual setting where speakers share more than one language. Code-switching Some linguists use the terms code-mixing and code-switching more or less interchangeably. Especially in formal studies of syntax, morphology, etc., both terms are used to refer to utterances that draw from elements of two or more grammatical systems. These studies are often interested in the alignment of elements from distinct systems, or on constraints that limit switching. Some work defines code-mixing as the placing or mixing of various linguistic units (affixes, words, phrases, clauses) from two different grammatical systems within the same sentence and speech context, while code-switching is the placing or mixing of units (words, phrases, sentences) from two codes within the same speech context. The structural difference between code-switching and code-mixing is the position of the altered elements—for code-switching, the modification of the codes occurs intersententially, while for code-mixing, it occurs intrasententially. In other work the term code-switching emphasizes a multilingual speaker's movement from one grammatical system to another, while the term code-mixing suggests a hybrid form, drawing from distinct grammars. In other words, code-mixing emphasizes the formal aspects of language structures or linguistic competence, while code-switching emphasizes linguistic performance.