technology used to detect and locate proteins, antibodies or other biomolecules. This method involves combining a fluorescently labeled antibody with the molecule to be tested to form an immune complex that emits fluorescence. Through fluorescence microscopy, researchers can visualize the location and expression of target molecules at the cellular or tissue level. IF technology is widely used in biomedical research, clinical diagnosis and drug development, providing an important tool for in-depth understanding of biology and disease mechanisms.