Humans are capable of conscious feelings that concern the state of the body, such as pain, itch, muscular and visceral sensations, hunger, thirst, sexual desire, and air need. The classification of such feelings, and particularly their relation to the more classical sensory systems for vision, audition, and touch, as well as to emotions such as anger and happiness, has been a matter of ongoing debate. Unlike sight, smell, and hearing that have dedicated sensory organs, there are no dedicated bodily organs for position and movement sense, pain, and many other modalities. Instead, developments in physics, anatomy, and physiology since the nineteenth century have given rise to a wide interest in mapping and classifying the senses with reference to criteria such as the nature of the stimulus, anatomy and location of receptors across body parts, the pathways to and the representation of the signal at the central nervous system (CNS), as well as the quality of the experience. This interest led to a number of classifications of the senses; for example, in exteroceptive (their receptive field “lies freely open to the numberless vicissitudes and agencies of the environment” Sherrington, 1910, p. 132), interoceptive (sensory receptors located within the body and primarily in the viscera), and proprioceptive sensations (receptors in muscles, tendons, and joints detecting position and movement of the body). Since this influential classification (see Ceunen, Vlaeyen, & Van Diest, 2016 for a review), exteroceptive and proprioceptive systems have received far more attention than interoceptive modalities. However, as this volume exemplifies, this has changed in the two last decades. On the one hand, theories and studies in affective neurosci-ence (eg Damasio, 2010) have brought to the foreground William James's older idea that interoceptive sensations may lie at the heart of our emotions and self-awareness. On the other hand, progress in anatomy and physiology has urged certain researchers (eg Craig, 2002) to propose alternative classifications of the senses that include a more encompassing definition of interoception as the sense of the physiological condition of the entire body, not just the viscera.