PI first appeared in the application of scientific research projects in Europe and America. The National Science Foundation (NSF) is defined as "an individual who is appointed by the transferee and is in charge of the scientific and technological direction of the project with the consent of the National Natural Science Foundation of the United States", and points out that "this term is generally used in the research field", while another term PD (project director) with the same concept is mostly used in science and engineering education or other fields. The National Institutes of Health (NIH) is defined as "an individual recognized by the applicant who has certain rights and responsibilities to guide the projects or plans supported by the fund".
In short, PI is the individual who has the leading power and guiding power to the project in charge, that is, the project leader. It is worth noting that according to the definition of similar institutions abroad, as long as the applicant has obtained the project funding, it can be considered as the PI of the project, and no matter whether it is an assistant professor, an associate professor or a professor, as long as there is enough research funding, doctors, postdocs and scientific and technological personnel can be recruited. This qualification should not be granted by the administrative agency of the applicant's unit. As long as the applicant has obtained the project funding, it can be regarded as the PI of the project. This management mode of scientific research projects is usually called PI system. To sum up, PI system is a scientific research management mechanism with PI as the core to allocate human resources, umbrella cost accounting of project funds as the core to allocate financial resources, and realizing the enjoyment of scientific research resources as the core to allocate material resources.
As a new scientific research organization and management model in China, PI production has received unprecedented attention and attention from the scientific community. As an imported product, domestic scientific circles often annotate PI system with Chinese characters, such as "the person in charge of the research group", "the person in charge of the project", "the chief scientist" and "the academic leader".