A Blue Zone is a region of the world where people commonly live active lives past the age of 100 years. Scientists and demographers have classified these longevity hot-spots by having common healthy traits and life practices that result in higher-than-normal longevity.
The name Blue Zone seems to have been first employed in a scientific article by a team of demographers working on centenarians in Sardinia in 2004.

Blue Zones is also the name of a related project from Dan Buettner

Dan Buettner

Dan Buettner is an American explorer, educator, author, public speaker and co-producer of an Emmy Award-winning documentary who also holds three world records for endurance bicycling. He is the founder of the online Quest Network, Inc., which provides opportunities for students to interactively...

's Quest Network, Inc.
Five Blue Zones have been identified by Buettner:

• Sardinia
  Sardinia
  Sardinia is the second-largest island in the Mediterranean Sea . It is an autonomous region of Italy, and the nearest land masses are the French island of Corsica, the Italian Peninsula, Sicily, Tunisia and the Spanish Balearic Islands.The name Sardinia is from the pre-Roman noun *sard[],...
  
  , Italy
  Italy
  Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
  
  : One team of demographers found a hot spot of longevity in mountain villages where men reach the age of 100 years at an amazing rate.
• The islands of Okinawa, Japan
  Japan
  Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
  
  : Another team examined a group that is among the longest lived on Earth.
• Loma Linda, California
  Loma Linda, California
  Loma Linda is a city in San Bernardino County, California, United States, that was incorporated in 1970. The population was 23,261 at the 2010 census, up from 18,681 at the 2000 census...
  
  : Researchers studied a group of Seventh-day Adventists
  Seventh-day Adventist Church
  The Seventh-day Adventist Church is a Protestant Christian denomination distinguished by its observance of Saturday, the original seventh day of the Judeo-Christian week, as the Sabbath, and by its emphasis on the imminent second coming of Jesus Christ...
  
   who rank among America's longevity all-stars.
• Nicoya Peninsula
  Nicoya Peninsula
  The Nicoya Peninsula is a peninsula on the Pacific coast of Costa Rica and lies in the Guanacaste Province in the north, and the Puntarenas Province in the south. It is located at . It varies from 19 to wide and is approximately long, and forms the largest peninsula in the country. It is known...
  
  , Costa Rica
  Costa Rica
  Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
  
  : The Nicoya Peninsula was the subject of research on a Quest Network expedition which began on January 29, 2007.
• Icaria
  Icaria
  Icaria, also spelled Ikaria , is a Greek island in the Aegean Sea, 10 nautical miles southwest of Samos. It derived its name from Icarus, the son of Daedalus in Greek mythology, who fell into the sea nearby. Administratively the island forms a separate municipality within the Ikaria peripheral...
  
  , Greece
  Greece
  Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
  
  : The April '09 expedition to the island of Ikaria uncovered the location with the highest percentage of 90 year-olds on the planet - nearly 1 out of 3 people make it to their 90s.