In the duality, the agency has much more influence on its lived environment than past structuralist theory had granted.
The key to Giddens' explanation is his focus on the knowledgeability of the agent and the fact that the agency cannot exist or be analysed separately from its structure.
The system of interaction includes in itself "rules" of the language such as syntax but also leaves room for interpretations or the creation of completely new words.
The system of interaction is responsible for maintaining a certain standard of consistency in order for the language to make sense to both the speaker and the interpreter.
The phrase is used in Chomsky by John Lyons to illustrate the differences between human and animal communication.