Tremble, or shiver, is a physical response characterized by small, rapid movements of the body. This reaction often occurs due to cold temperatures, fear, or excitement. When the body feels cold, muscles contract and relax quickly to generate heat, resulting in a shivering sensation. Shivering can also be a response to emotional stimuli, such as anxiety or anticipation. In these cases, the body releases adrenaline, which can trigger involuntary muscle contractions. This response is a natural way for the body to cope with various environmental and emotional factors, helping to maintain homeostasis.