Success of orthodontic treatment of a patient be subject to accurate diagnosis and treatment planning. The purpose of this book is to provide details on clinical two-dimensional cephalometrics, an important part of diagnosis and treatment planning. Currently, clinical orthodontics is transitioning from the two-dimensional (2D) world to the three-dimensional (3D) world. Cephalometry, a measure of straight lines and angles of the hard and soft tissue of the face and cranium, is evolving into measures of areas and volumes that will need to be interpreted for clinical decisions and evaluation of outcomes. However, clinicians got to understand 2D cephalometry to be ready to apply it better in 3D cephalometry. An effort was made to concise information available on cephalometrics in the literature to broaden the aspects of the role of it in diagnosis and treatment planning.