The planning function is defined as the process of developing the mission and objectives of the organization, and specifying the means by which the organization is to achieve them. Several levels of planning activities occur, ranging from broad based generalized approaches to explicit and specific descriptions of actions to accomplish specific tasks.
Planning is a function of primacy.
We mean by this that planning is an activity that is important to every activity of the managerial process. This leads to assumptions about the future we must make in order to begin the process. Managers call these assumptions premises. Priorities among desired outcomes are also established. This is the assigning of differential levels of importance to various objectives.