Any occupation which requires advanced and specialized education or training can be classified as professional services. Some professional services demand holding professional licenses such as doctors, engineers, doctor, lawyers and architects. While, other professional services require providing specialist business support to businesses across different sectors. Accounting, management consulting, tax advice are such professional services.
These professions might require getting licensed or registered with the state depending on the rules and regulations. Professional service providers can be sole proprietors, partnerships or corporations.
Prices for services, even within the same field, may vary greatly depending upon various factors such as skill, expertise, experience, reputation and capacity. Service providers might charge fixed rates, or charge in relation to the number of hours worked, number of people engaged, or charge in relation to benefits generated by the project.