Since the late 1980s, rhinologic surgeons have embraced image-guided surgery (IGS) technology, since IGS provides additional localization data during both simple and complex procedures of the paranasal sinuses and adjacent skull base. All IGS systems operate in accordance with well-described principles, and to a large degree, all IGS systems incorporate similar software and hardware. Registration is the process of aligning the preoperative imaging data set (typically CT scan) with the intraoperative anatomy. Surgeons must confirm the accuracy (formally known as target registration error) of the IGS system by confirming localizations against known anatomic structures. TRE can vary throughout the surgery and even in different parts of the sinuses during a single surgery for a variety of well-described reasons. Special IGS techniques include the use of fused CT-MR images and 3D CT angiography images. In recent years, both virtual reality and augmented reality tools have been added to IGS.