Professional
A professional is a member of a profession or any person who earns their living from a specified activity. The term also describes the standards of education and training that prepare members of the profession with the particular knowledge and skills necessary to perform the role of that profession. In addition, most professionals are subject to strict codes of conduct enshrining rigorous ethical and moral obligations. Professional standards of practice and ethics for a particular field are typically agreed upon and maintained through widely recognized professional associations. Some definitions of "professional" limit this term to those professions that serve some important aspect of public interest and the general good of society.
In some cultures, the term is used as shorthand to describe a particular social stratum of well-educated workers who enjoy considerable work autonomy and who are commonly engaged in creative and intellectually challenging work.
Trades
In narrow usage, not all expertise is considered a profession. Although sometimes incorrectly referred to as professions, occupations such as skilled construction and maintenance work are more generally thought of as trades or crafts. The completion of an apprenticeship is generally associated with skilled labour, or trades such as carpenter, electrician, mason, painter, plumber and other similar occupations. A related distinction would be that a professional does mainly mental work, as opposed to engaging in physical work.