Discourse Analysis

special words which are used to begin the conversation 

refers to the process by which people in a conversation decide who is to speak next. It depends on both cultural factors and subtle cues.

Reciprocal action or influence:
e.g. ongoing interaction between the two languages

an utterance that has performative function in language and communication

it is a form of interactive, spontaneous communication between two or more people. Typically, it occurs in spoken communication, as written exchanges are usually not referred to as conversations.