While the number of occupations known as "professions" has increased, studies in economics have not secured a grasp of old and new professions within the same context. One reason is that they do not view certain occupations in terms of the concept of "profession" as an ideal type. This study reconsiders many aspects of professions and extracts the most notable features that characterize an occupation as a profession. The most crucial characteristic of an ideal profession type is a codified body of knowledge. A profession needs to be socially accepted as being highly developed and not substitutable. In addition, the occupational function of a profession involves urgency and indispensability, and the profession must be at the vertex of its field while using a common body of knowledge. In categorizing modern professionals based on these criteria, we arrived at five types: established professions, new professions, semi-professions (A), semi-professions (B), and skilled workers and experts.