؟What is code switching? in the English language

Code switching is when a speaker of one language uses another language during  verbal communication. it can happen at lexical level, phrasal level or sentence level depending on the switchers proficiency in the language he/she is switching

le code switching est le fait d'alterner deux ou plusieurs langues dans une communication entre locuteurs de la même société 

In linguistics, code-switching  is switching between two or more languages, or (language varieties), in the context of a single conversation. 

In linguistics, code-switching occurs when a speaker alternates between two or more languages, or language vraties, in the context of a single conversation. Multilinguals, speakers of more than one language, sometimes use elements of multiple languages when conversing with each other. Thus, code-switching is the use of more than one linguistic variety in a manner consistent with the syntax and  phonology of each variety.

Code is a process in wich a person switches from one language to another in the same context.

code switching concerns about the shift from language to another while speaking. 

Code-switching is the practice of moving between variations of languages in different contexts. Everyone who speaks has learned to code-switch depending on the situation and setting. In an educational context, code-switching is defined as the practice of switching between a primary and a secondary language or discourse.