Planning is an essential managerial function undertaken at every level of an organization to determine future courses of action. The document discusses the process of planning and compares the planning approaches of two companies, Company A and Company B. While both companies followed the steps of planning, only Company A was successful because Company B's manager made several mistakes in implementation, such as failing to involve employees, link strategic plans to budgets, address resistance to change, and review plans regularly. Proper planning requires addressing these implementation factors for success.