Staff and line are names given to different types of functions in organizations. A "line function" is one that directly advances an organization in its core work. This always includes production and sales, and sometimes also marketing. A "staff function" supports the organization with specialized advisory and support functions. For example, human resources, accounting, public relations and the legal department are generally considered to be staff functions. Both terms originated in the military.
Organizations begin as line-only, with line manager having direct control over all activities, including administrative ones. Only later, as organizations grow in size, do they add staff positions.
Line managers have total authority over those who report directly to them, but staff workers have primarily advisory authority. Their function is to create, develop, collect and analyze shop information, which flows to line workers in the form of advice.
Staff positions can have four kinds of authority: "advise authority," with line managers choosing whether or not to seek advice from the staff person, and deciding what to do with the advice once they get it; "compulsory advice" or "compulsory consultation" in which line managers must consider the staff person's advice, but can choose not to heed it; "concurrent authority," in which the line manager cannot finalize a decision without the agreement of the staff person, and "functional authority" in which the staff person has complete formal authority over his or her area of specialty, such as the Personnel Department in the United States Navy. The Staff Officer in this role is typically a rank of O-3(LT) or O-4(LCDR) and is granted authority over personnel assigned to those specific roles.  Common types of functional authority for staff positions include authority over recruiting standards, reimbursement policies and quality standards.
Staff workers derive influence from expert authority or "authority of knowledge," from their control of information which may be vital to line managers, and from their closer access to upper management.
It is common for line and staff workers to come into conflict. Staff specialists say line workers avoid and ignore them, and line workers say staff workers lack expertise in the organization's core work, distract them, and get in their way. American organizational sociologist Melville Dalton attributed this to "the conspicuous ambition and individualistic behavior among staff managers," staff's anxiety to justify their existence, and the dependence of highly ranked staff managers on line managers. Other management theorists have observed that line managers sometimes resent staff advisors for being younger and better-educated than they are. Others attribute the problem to staff managers not realizing that even though they have been delegated authority in particular areas, their primary role is to serve and support line managers. Management textbooks advise resolving line-staff conflict by explicitly recognizing the mutual dependency of the two, making it clear what the staff role is, de-emphasizing any controlling elements of the staff role, having staff deliberately set out to win the confidence and trust of line workers, and emphasizing the staff role as part of the team.
Most MBA graduates have aspired to work in staff positions using their analytical skills to advise line managers. In the 1980s when many large companies began downsizing to reduce their number of employees, staff jobs were eliminated more often than line jobs. (For example, IBM cut its staff positions from 7,000 to 3,000, and CBS cut hundreds of staff positions from its New York headquarters.) Thereafter, line jobs began increasingly to contain some analytic functions, and more new MBA graduates began aspiring to line functions.
Management experts believe organizations should minimize their investment in staff positions, because they increase costs while not directly contributing to the organization's goals. Increasingly organizations, especially smaller ones, are beginning to move away from line-staff structures to structures that are more hybrid or matrixed.