Anxiety is a feeling of tension associated with a sense of threat of danger when the source of the danger is not known.  In contrast, fear is a feeling of tension that is associated with a known source of danger.  It is normal for us to have some mild anxiety present in our daily lives.  Anxiety warns us and enables us to get ready for the "fight or flight" response.  However, heightened anxiety is emotionally painful.  It disrupts a persons daily functioning.