Code-switching refers to alternating between two or more languages or language varieties in a single conversation. It occurs when multilingual speakers incorporate elements of the other languages they know into the one they are primarily using. Code-switching happens both intersententially, between sentences, and intrasententially, within sentences. It is governed by syntactic constraints and tends to occur at points where the grammar of the languages aligns. Borrowing involves adopting words from another language, while code-switching can happen at the syntactic level or above.

1. CODE/ CODE SWITCHING

2.  code-switching is the concurrent use
of more than one language, or
language variety, in conversation.
 code-switching is the use of more
than one linguistic variety in a
manner consistent with the syntax
and phonology of each variety.

3.  Multilinguals - people who speak
more than one language - sometimes
use elements of multiple languages in
conversing with each other.

4.  A loanword (or loan word) is a word
borrowed from one language and
incorporated into another.
 A calque or loan translation is a
related concept where the meaning or
idiom is borrowed rather than the
lexical item itself..

5. A pidgin
 A pidgin ( /ˈpɪdʒɪn/), or pidgin language,
is a simplified language that develops as
a means of communication between two
or more groups that do not have a
language in common
 . A pidgin is not the native language of
any speech community, but is instead
learned as a second language. A pidgin
may be built from words, sounds, or
body language from multiple other
languages and cultures. Pidgins usually
have low prestige with respect to other
languages.

6. A Creole
 is a stable natural language developed
from the mixing of parent languages;
creoles differ from pidgins in that they
have been nativized by children as their
primary language, making them have
features of natural languages that are
normally missing from pidgins.
 The vocabulary of a creole language
consists of cognates from the parent
languages, though there are often clear
phonetic and semantic shifts.

7. Language transfer
 Language transfer (language
interference) refers to speakers or
writers applying knowledge from their
native language to a second
language.

8. Code mixing
 Code mixing is a thematically related
term, but the usage of the terms code-
switching and code-mixing varies.
Some scholars use either term to
denote the same practice, while others
apply code-mixing to denote the
formal linguistic properties of said
language-contact phenomena, and
code-switching to denote the actual,
spoken usages by multilingual
persons.

9. Social motivations for code-
switching
 Code-switching relates to, and
sometimes indexes social-group
membership in bilingual and
multilingual communities. Some
sociolinguists describe the
relationships between code-switching
behaviors and class, ethnicity, and
other social positions. In addition,
scholars in interactional linguistics and
conversation analysis have studied
code-switching as a means of
structuring talk in interaction.

10. diglossia
 , diglossia ( /daɪˈɡlɒsiə/; two languages)
refers to a situation in which two dialects
or languages are used by a single
language community. In addition to the
community's everyday or vernacular
language variety (labeled "L" or "low"
variety), a second, highly codified variety
(labeled "H" or "high") is used in certain
situations such as literature, formal
education, or other specific settings, but
not used for ordinary conversation

11. Convergence
 Convergence - is a type of contact-
induced change whereby languages
with many bilingual speakers mutually
borrow morphological and syntactic
features, making their typology more
similar.

12. Mechanics of code-switching
 Mechanics of code-switching
 Code-switching mostly occurs where the
syntaxes of the languages align in a
sentence; thus, it is uncommon to switch
from English to French after an adjective
and before a noun, because, in French,
adjectives usually follow nouns. Even
unrelated languages often align
syntactically at a relative clause
boundary or at the boundary of other
sentence sub-structures.

13. Borrowing / code-switching;
 the difference between borrowing
(loanword usage) and code-switching;
generally, borrowing occurs in the
lexicon, while code-switching occurs
at either the syntax level or the
utterance-construction level.

14. Some proposed constraints
are
The Free-morpheme Constraint: code-switching cannot occur
between bound morphemes.
 The Equivalence Constraint: code-switching can occur only in
positions where "the order of any two sentence elements, one
before and one after the switch, is not excluded in either
language." Thus, the sentence: "I like you porque eres
simpático." ("I like you because you are nice.") is allowed
because it obeys the relative clause formation rules of
Spanish and English.
 The Closed-class Constraint: closed class items (pronouns,
prepositions, conjunctions, etc.), cannot be switched.
 The Matrix Language Frame model distinguishes the roles of
the participant languages
 The Functional Head Constraint: code-switching cannot occur
between a functional head (a complementizer, a determiner,
an inflection, etc.) and its complement (sentence, noun-
phrase, verb-phrase).

15. Types of switching
 Scholars use different names for various
types of code-switching.
 Intersentential switching occurs outside the
sentence or the clause level (i.e. at sentence
or clause boundaries).[27] It is sometimes
called "extrasentential" switching.
 Intra-sentential switching occurs within a
sentence or a clause.
 Tag-switching is the switching of either a tag
phrase or a word, or both, from language-B to
language-A, (common intra-sentential
switches)
 Intra-word switching occurs within a word,
itself, such as at a morpheme boundary.