"Personnel" is an antiquated term for referring to what is now commonly called "Human Resources". The Human Resources department does not the decision on who should be hired or fired. This is usually left up to the department that the employee works in. Human Resoucres screen applicants for positions, ensure compliance with employment laws, administer training and development programs, manage employee benefits, and perform internal investigations (like sexual harassment claims). They also are involved in recruiting and they do research to ensure that their compensation programs are in line with the competition. They also maintain permanent records for all employees and are usually the ones that answer questions. They may also maintain the company's organizational chart and may maintain a database of the company's various jobs, their descriptions, and their performance requirements.