In simple terms, Easton's behavioral approach to politics, proposed that a political system could be seen as a delimited (i.e. all political systems have precise boundaries) and fluid (changing) system of steps in decision making. Greatly simplifying his model:Easton, David. (1965). A Systems Analysis of Political Life. New York: Wiley.
Step 1. changes in the social or physical environment surrounding a political system produce "demands" and "supports" for action or the status quo directed as "inputs" towards the political system, through political behavior.
Step 2, these demands and supporting groups stimulate competition in a political system, leading to decisions or "outputs" directed at some aspect of the surrounding social or physical environment.
Step 3, after a decision or output is made (e.g., a specific policy), it interacts with its environment, and if it produces change in the environment, there are "outcomes."
Step 4, when a new policy interacts with its environment, outcomes may generate new demands or supports and groups in support or against the policy ("feedback") or a new policy on some related matter.
Step 5, feedback leads back to Step 1, it's a......