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. PIs often work in academic, government, or private research settings and are typically experts in their field. In addition to conducting research, principal investigators are also responsible for securing funding, often through grants from organizations like the National Institutes of Health or National Science Foundation. They may supervise a team of researchers, students, and staff, guiding them in their roles and fostering collaboration throughout the project.