There are three types of managers: top managers who make organization-wide decisions, middle managers who oversee first-line managers, and first-line managers who directly manage non-managerial employees. Managerial roles include interpersonal roles like leadership, informational roles like monitoring, and decisional roles like resource allocation. Effective managers need technical skills for their specific job, human skills to work well with others, and conceptual skills to think strategically about complex organizational issues.