Anxiety is a feeling of unease. Everybody gets anxious when faced with a stressful situation, eg before an exam or an interview or during a worrying time such as illness. It's normal to feel anxious when you face something difficult or dangerous and mild anxiety can be a positive and useful experience. Excessive anxiety is often associated with other mental health problems, eg depression. Anxiety is only considered to be a mental health problem when it's long lasting, severe and is interfering with every day activities.
Attribution: BUPA