Anxiety is an unpleasant emotion characterized by fear, apprehension, or dread. Anxiety is usually felt as an unpleasant feeling in the chest or abdomen. There is also a sense that something bad will happen. Anxiety is often accompanied by physical symptoms, which include rapid heart rate, muscle tension, and sweating.
Anxiety is from the emotional part of the brain called the limbic system, whereas worry is from the thinking part of your brain called the cortex. Stress is the physical response to a threat or stressor, and this is mediated by the activation of the fight or flight response, also known as the adrenaline response.