All people feel anxiety. Whether it is the butterflies in your stomach before you ask someone out on a date, or the rush of anxiety that propels you out the door when you are running late. Often these feelings of anxiety are uncomfortable, but anxiety is a normal part of being a human being.
In fact, anxiety, panic, and worry are all part of the way humans experience fear. Each of these aspects involves the anticipation of danger or threat. We define anxiety as a normal, innate emotional alarm response to the anticipation of danger or threat. This means that fear is part of our biological make-up as human beings. We don't learn how to become anxious--we are born with it because it helps us to survive. Anxiety serves as an "alarm" to protect us from harmful aspects of our environment. Taken together, this definition means that anxiety is an innate, protective response to our environment.
Panic is similar to anxiety, and we define panic as a normal, innate emotional alarm response to the perception of immediate danger or threat. Similar to anxiety, panic is triggered when the threat is immediate--a burglar breaking into your home would likely elicit panic, while the fear of such an event happening in the future would generate anxiety.
Worry is also a normal, adaptive response to threat. Worry is a mental strategy that is used to avoid future danger. Anxiety serves to notify us of an upcoming threat or danger, and worry stimulates us to find a solution to a problem or a way of escaping from the danger.