Not so long ago the amygdala was an unclear region of the brain. Nowadays it is assumed that the amygdala is playing a key role in emotions, especially in the perception of fear. The amygdala is a crucial component that enables humans and animals to detect and to respond to threats. When the amygdala is damaged the ability to learn and respond to threats becomes impaired. This paper reviews data that highlights internal processes of the amygdala as well as external amygdala processes. Further, it discusses how the amygdala contributions to fear related emotions and memory. Additionally the paper discusses what the costs are to the concept of fear in humans and animals when the amygdala is damaged. In sum, the paper presents a variety of studies conducted both on humans and animals, using brain imaging machines and fear conditioning that confirms the importance of the amygdala in the perception of fear.