Anxiety is a feeling of dread and uneasiness about something real or imagined
“Something real” refers to an event about which you predict a negative outcome. For example, you are uncomfortable with your child playing on a swing, because you are convinced that she will fall and hurt herself.
“Something imagined” refers to a scenario that you create in your head about something that hasn’t happened yet. For example, you are uncomfortable with riding the subway, because you fear getting stuck in it without air.