A Principal Investigator (PI) is the lead researcher responsible for planning, conducting, and managing a research project. They oversee the project's design, implementation, and analysis, ensuring that it meets scientific and ethical standards. The PI is often the primary author of research proposals and is accountable for the project's budget and timeline. In academic and scientific settings, the PI typically holds a senior position, such as a professor or a senior researcher. They often collaborate with other researchers, students, and institutions, guiding the research team and facilitating communication among all parties involved in the project.