Understanding the Department of Homeland Security discusses why the Department of Homeland Security (DHS) -- the largest and the newest department of government -- was established and then takes a detailed look at the role of the 22 different federal departments and agencies that were incorporated into it. DHS has more than 240,000 employees in jobs that range from aviation and border security to emergency response, from cybersecurity analyst to chemical facility inspector. Its duties are wide-ranging, but the goal is clear -- keeping America safe. Features an analytical look at the Department of Homeland Security and all its component agencies and a list of all the major homeland security incidents over the last 100 years.

The rationale behind the creation of the DHS -- The first nine months following the September 11 attacks -- About the Department of Homeland Security -- The Federal Emergency Management Agency -- The Transportation Security Administration -- United States Citizenship and Immigration Services -- United States Customs and Border Protection -- United States Coast Guard (USCG) -- United States Immigration and Customs Enforcement -- United States Secret Service -- Science and Technology Directorate -- Department Administration and Programs -- Other departments, agencies, and organizations.