The American Psychological Association (APA) Dictionary of Psychology defines “anxiety (n) an emotion characterized by apprehension and somatic symptoms of tension in which an individual anticipates impending danger, catastrophe, or misfortune. The body often mobilizes itself to meet the perceived threat: Muscles become tense, breathing is faster, and the heart beats more rapidly. Anxiety may be distinguished from fear both conceptually and physiologically, although the two terms are often used interchangeably. Anxiety is considered a future-oriented, long-acting response broadly focused on a diffuse threat, whereas fear is an appropriate, present-oriented, and short-lived response to a clearly identifiable and specific threat. —anxious adj.” 

According to the American Psychiatric Association “anxiety is a normal reaction to stress and can be beneficial in some situations. It can alert us to dangers and help us prepare and pay attention. Anxiety disorders differ from normal feelings of nervousness or anxiousness and involve excessive fear or anxiety.” 

Similarly, the Mayo Clinic indicated that “experiencing occasional anxiety is a normal part of life. However, people with anxiety disorders frequently have intense, excessive, and persistent worry and fear about everyday situations.” Anxiety is what we feel when we are worried, tense, or afraid. It is our body’s response to stress. 

According to The National Institute of Mental Health signs and symptoms of anxiety are as follows: 

• Feeling restless, wound-up, or on-edge. 
• Being easily fatigued. 
• Having difficulty concentrating. 
• Being irritable. 
• Having headaches, muscle aches, stomachaches, or unexplained pains. 
• Difficulty controlling feelings of worry. 
• Having sleep problems, such as difficulty falling or staying asleep. 

Psychotherapy can help many people who experience anxiety. Cognitive Behavioral Therapy, Exposure Therapy and Acceptance and Commitment Therapy are often used. Psychotropic medications can be helpful to relieve symptoms of anxiety but is not a cure. Some people might benefit from joining a self-help support group or by employing effective stress management techniques. 

References: 

https://dictionary.apa.org/anxiety 

https://www.nimh.nih.gov/health/topics/anxiety-disorders 

https://www.psychiatry.org/patients-families/anxiety-disorders/what-are-anxiety-disorders

https://medlineplus.gov/anxiety.html 

https://www.mayoclinic.org/diseases-conditions/anxiety/symptoms-causes/syc-20350961