Direct laryngoscopy should be preceded by airway assessment and discussing rescue strategies with assisting staff. The initial plan and rescue techniques should be based on an understanding of normal airway anatomy and its variants. This chapter uses the two curve theory and the three column model to describe and functionally classify both the normal and difficult airways. This classification then provides the operator with an understanding of the various causes of difficult airways and how they are related to each other and airway morphology (two curve theory). These two concepts form the basis for the decision process to performing direct laryngoscopy and choosing the right laryngoscope blade for the job. Endobronchial intubation is discussed in detail.