Near-infrared (NIR, 700-1700 nm) fluorophores serve as fundamental components in NIR fluorescence (NIRF) imaging systems owing to their unique optical characteristics. These fluorophores demonstrate remarkable molecular specificity that facilitates both precise biomarker localization and real-time tracking in biological processes, making NIRF imaging valuable for diagnostic applications and intraoperative guidance. This chapter systematically reviews the major classes of NIR fluorophores, with particular emphasis on their structural features, photophysical properties, and emerging biomedical applications.