A supervisor, foreman, foreperson, team leader, overseer, cell coach, facilitator, or area coordinator is a manager in business. The US Bureau of Census has four hundred titles under the supervisor classification.
An employee is a supervisor if they have the power and authority to do the following actions (according to the Ontario Ministry of Labour):
Give instructions and/or orders to subordinates.
Be held responsible for the work and actions of other employees.
If an employee cannot do the above, legally he is probably not a supervisor, but in some other category, such as lead hand.
A supervisor is first and foremost an overseer whose main responsibility is to ensure that a group of subordinates get out the assigned amount of production, when they are supposed to do it and within acceptable levels of quality, costs and safety.
A Supervisor is responsible for the productivity and actions of a small group of employees. The Supervisor has several manager like roles, responsibilities, and powers. Two of the key differences between a Supervisor and a Manager are (1) the Supervisor does not typically have "hire and fire" authority, and (2) the Supervisor does not have budget authority.
Lacking "hire and fire" authority means that a Supervisor may not recruit the employees working in the Supervisor's group nor does the Supervisor have the authority to terminate an employee. The Supervisor may participate in the hiring process as part of interviewing and assessing candidates but the actual hiring authority rests in the hands of a Human Resource Manager. The Supervisor may recommend to management that a particular employee be terminated and the Supervisor may be the one who documents the behaviors leading to the recommendation but the actual firing authority rests in the hands of a Manager.
Lacking budget authority means that a Supervisor is provided a budget developed by management within which constraints the Supervisor is expected to provide a productive environment for the employees of the Supervisor's work group. A Supervisor will usually have the authority to make purchases within specified limits. A Supervisor is also given the power to approve work hours and other payroll issues. Normally, budget affecting requests such as travel will require not only the Supervisor's approval but the approval of one or more layers of management.
As a member of management, a supervisor's main job is more concerned with orchestrating and controlling work rather than performing it directly.

A supervisor in the workplace has four distinctly separate sets of responsibilities. The supervisor's first duty is to represent management and the company. It is the supervisor’s job to organize his/her department and employees, visualize future impacts and needs, energize the employees to get their tasks done and supervise their work ensuring that the productivity and quality standards are met. To ensure that this is done, the supervisor makes certain that his employees have the training, the tools and the material that they need to carry out their duties.
Another important part of the job is to act as a middleman and buffer between the employees who actually do the job and the rest of the organization. The supervisor makes sure that his employees’ pay is correct, their vacation pay arrives on time and they receive proper care if they get injured on the job.
The supervisor also has legal responsibilities to ensure that his area of responsibility is free of safety violations, all employees received proper training and that all human rights are upheld. Supervisors are also responsible for the health and safety of all their subordinates and to ensure that they work in a harassment-free environment.
It is also the supervisor’s responsibility to develop all the potential leaders that work under him/her so that the company can identify and place all the employees who demonstrate that they have the interest and abilities to be promoted or transferred to better positions.