This chapter will provide a comprehensive overview of the nature of equines based on a broad review of equine behavior and psychology. The chapter opens with a discussion of the evolution of modern-day equines. Next, the chapter will discuss the concept of equine emotion and how it is influenced by the equine’s identity as a mammal and as a prey animal. The chapter will then explain the equine’s mentality as a prey animal and how this mentality influences the equine’s relationship with humans. The chapter will then describe how equines understand and operate in the world based on their five senses. The following section presents a discussion of equine social behaviors including herd dynamics, equine communication, and social bonding. The chapter concludes with a review of equine temperament and personality.