Final answer:
All anxiety disorders share the characteristic of excessive, persistent fear and anxiety that is long-lasting and impairs daily functioning.
Step-by-step explanation:
A common characteristic of all anxiety disorders is excessive, persistent fear and anxiety. While specifics can vary among different types of anxiety disorders, such as obsessive-compulsive disorder (OCD), panic disorders, posttraumatic stress disorder (PTSD), and phobias, the unifying feature is the duration and intensity of the fear and anxiety experienced that lasts for an extended period and disrupts daily life. This is distinct from the normal reactions to stress that individuals might feel temporarily.