This chapter provides readers an insight into the basic structures and functions of the human brain, which are essential to better understand the contents. In this chapter, the basic structures, functions, and types of neurons and the transmission of information in various forms across synapses are discussed. This chapter offers knowledge about the somatic and autonomic nervous system and anatomical and physiological characteristics of the divisions and lobes of the brain. A basic concept of human memory and intelligence is discussed. It also provides various facts about the biology of the brain for a better and observable understanding of the highly complex mechanisms involved in the brain.