This book deals with the paranasal sinuses. Their are four paranasal sinuses namely frontal, maxillary ethmoid, and sphenoid sinuses. Paranasal sinuses are indeed one of the most important parts of the facial skeleton. Their complex anatomy, functions, and variations make them an interesting topic to study. This book intends to provide an overview of the paranasal sinuses and by sampling the literature, exemplify their importance to the oral physician and radiologist as "Each world contains a myriad of smaller worlds", making the understanding of paranasal sinuses complex in a simple and easy way.