Stress is a biological term which refers to the consequences of the failure of a human or animal body to respond appropriately to emotional or physical threats to the organism, whether actual or imagined. It includes a state of alarm and adrenaline production, short-term resistance as a coping mechanism, and exhaustion.

It refers to the inability of a human or animal body to respond. Common stress symptoms include irritability, muscular tension, inability to concentrate and a variety of physical reactions, such as headaches and elevated heart rate. (Wikipedia)

Although stress can help you rise to a challenge, becoming over stressed or chronically stressed can interfere with your performance levels, physical health and relationships.

Common causes of stress include problems at work or in relationships, renovation or relocation, retrenchment or unemployment, a traumatic event, illness or disability, workplace bullying, change and unrealistic expectations placed on you.

It may not be possible to remove all the stressors from your life, however learning how to better manage your stress may help you to get things done.

Source: http://www.wikipedia.com