A professional is a person who is paid to undertake a specialized set of tasks and to complete them for a fee. The traditional professions were doctors, engineers, lawyers, architects and commissioned military officers. Today, the term is applied to nurses, accountants, educators, scientists, technology experts, social workers, artists, librarians (information professionals) and many more.
The term is also used in sports to differentiate amateur players from those who are paid--hence "professional footballer" and "professional golfer". Many companies include the word professional in their store name to imply the quality of their workmanship or service.