Anthrax: Anthrax is a serious disease caused by Bacillus anthracis, a bacterium that forms spores. A bacterium is a very small organism made up of one cell. A spore is a cell that is dormant (asleep) but may come to life with the right conditions. There are three types of anthrax: skin (cutaneous), lungs (inhalation), digestive (gastrointestinal).

Biological and chemical weapons: Biological weapons use biological agents which are infectious particles or toxins to cause illness and death in people and animals if they contaminated to water and food. Chemical weapons use chemical agents which can kill or incapacitate people and animals quickly. Some of them are odorless and difficult to detect.

Department of Homeland Security: The President George W. Bush established the Office of Homeland Security and the Homeland Security Council, following the tragic events of September 11. The officials of Department of homeland security develop and coordinate a comprehensive national strategy to strengthen protections against terrorist threats or attacks in the United States.

Domestic terrorism: Domestic terrorism involves groups or individuals whose terrorist activities are directed at our government or people in U.S. without foreign direction.

Electricity backout: Blackouts (or power outages) occur when the electricity supply to an area or building is cut.

International terrorism: International terrorism involves groups or individuals whose terrorist activities are foreign based and /or directly by countries or groups outside of the United States.

Protective measures: They are preplanned emergency response procedures under the threat conditions to deter terrorist attacks issued by Homeland Security Advisory System and federal agencies.

Sarin nerve gas: A colorless and odorless organophosphate gas. A dose of 0.5 mg is lethal for an adult. It is 26 times more deadly than cyanide gas and is 20 times more lethal than potassium cyanide. The vapor is slightly heavier than air, so it hovers close to the ground. The injured symptoms are headache, blurred vision, or visual darkness and psychological problems associated with posttraumatic stress disorder, brain damage.