The categorization of time
into discrete named blocks is called periodization
. This is a list of such named time periods
as defined in various fields of study. Major categorization systems include cosmological
(concerning the various time periods in the origin
and evolution of our universe
(concerning time periods in the origin and evolution
) and historical
(concerning time periods in the origin, evolution
Human time periods
Based on current and debatable evidence, the human species has found its origins starting from about 250,000 years ago - when homo began to develop. It is broadly divided into prehistorical (before history began to be recorded) and historical periods (when written records began to be kept).
, human prehistory
is subdivided around the three-age system
- The Stone Age
- In some regions the Stone Age is divided into the Paleolithic Age (Old Stone Age) and the Neolithic Age (New Stone Age).
- In other regions the Stone Age is divided into the Paleolithic Age, the Mesolithic Age (Middle Stone Age, also called the Epipaleolithic Age), and the Neolithic Age.
- The Copper Age (aka Chalcolithic Age). The Copper Age was not part of the original three-age system.
- The Bronze Age
- The Iron Age
The dates for each age can vary by region. On the geologic time scale, the Holocene epoch starts at the end of the most recent Ice age (about 9400 BC) and continues to the present. The beginning of Mesolithic is usually considered to correspond to the beginning of the Holocene epoch.
- Ancient history, Classical antiquity
- Middle Ages (Europe, 4th century - 15th century)
- Early Middle Ages European (500-1000 CE)
- Asuka period, Nara period, Heian period, Kamakura period, Muromachi period, and Azuchi-Momoyama period (Japan, 538 - 1603)
- Southern and Northern Dynasties, Sui Dynasty, Tang Dynasty, Period of Five Dynasties and Ten Kingdoms (China, 420 - 960), Liao Dynasty, Song Dynasty, Jin Dynasty (1115–1234), Western Xia Dynasty, Yuan Dynasty, and Ming Dynasty (China, 220 - 1644)
- Classic and Postclassic eras, Central America (200 - 1519)
- Gupta Empire, Pala Empire, Rashtrakuta, Hoysala Empire, and Kakatiya Empire (India, 280 – 1323)
- Islamic Golden Age (Islam, 700 - 1300)
- High Middle Ages (Feudalism) European military expansion (1000–1450 CE)
- Srivijaya (Indonesia, 3rd century to 14th century), Tarumanagara (358-723), Sailendra (8th & 9th centuries), Kingdom of Sunda (669-1579), Kingdom of Mataram (752–1045), Kediri (1045–1221), Singhasari (1222–1292), Majapahit (1293–1500)
- Chenla (Cambodia, 630 – 802) and Khmer Empire (Cambodia, 802 – 1432)
- Anterior Lý Dynasty and Triệu Việt Vương, Third Chinese domination, Khúc Family, Dương Đình Nghệ, Kiều Công Tiễn, Ngô Dynasty, The 12 Lords Rebellion, Đinh Dynasty, Prior Lê Dynasty, Lý Dynasty, Trần Dynasty, Hồ Dynasty, Fourth Chinese domination (Vietnam, 544 - 1427)
- Early Intermediate, Middle Horizon, Late Intermediate, Late Horizon (Peru, 200 - 1534)
- Late Middle Ages European (1300–1500 CE)
- Early modern period (Europe, 14th century - 18th century)
- The Renaissance (Europe, 14th century - 16th century)
- Age of Discovery (or Exploration) (Europe, 15th century - 17th century)
- Elizabethan period (United Kingdom, 1558 - 1603)
- The Protestant Reformation (Europe, 16th century)
- Jacobean Era (United Kingdom, 1603-1625)
- The Age of Enlightenment (or Reason) (Europe,18th century)
- Tokugawa shogunate (Japan, 1603 - 1868)
- Mughal Empire (India, 1526 - 1857)
- Ottoman Empire (Islam, 1299 – 1923)
- Qing dynasty (China, 1644 - 1912)
- Spanish hegemony (Americas, 16th century - 1820s; Europe, 16th and 17th century, Philippines, 1525 - 1898)
- Modern era (Europe, 18th century - 20th century)
- Industrial Revolution (Europe, United States, elsewhere 18th and 19th centuries)
- (along with early modern era) Age of European colonialism and imperialism
- Napoleonic Era (1799 - 1815)
- Georgian Era (United Kingdom, 1714 - 1830)
- Victorian era (United Kingdom, 1837 - 1901); British hegemony, much of world, around the same time period.
- Edwardian period (United Kingdom, 1901 - 1910)
- Meiji period (Japan, 1868 - 1912)
- Machine Age(1900 - 1945)
- World War I (Much of Earth, 1914 - 1918)
- Interwar period (Earth, 1918 - 1939 or 1937)
- World War II (Earth, 1937 or 1939 - 1945)
- Post-Modern (USA, 1949 - Present)
- Net Generation Era (present)
Various societies in the past have created calendars to record events, such as religious observances and agricultural tasks. A common characteristic of most known calendars is that they measure time in relation to a particular point in history, known as the epoch date. A period between epoch dates is known as a calendar era. 27!É
Mythological and astrological time periods
Cosmological time periods
13.7 billion years ago: The Big Bang
Because of the scales involved (both very large and very small), cosmological time periods are usually described in seconds. In this table, each row is defined in seconds after the Big Bang, with earliest at the top of the chart.
Formation of Population III stars
The first stars were formed from the Hydrogen
formed in the Big Bang
were short lived massive Population III stars
. Nuclear processes in these stars converted the Hydrogen and Helium into metals and other heavier elements. As the Population III stars
died these heavier elements were released.
Formation of Population II stars
Population II stars
contain metals formed in the Population III stars
. These were longer lived than the Population III stars and some of them are still around. In addition to the metals these inherited from the Population III stars the Population II stars also formed metals by nuclear reactions and when the stars died much of that material was returned to be used as the building blocks for the next generation of stars.
5 Billion Years ago - Formation of Population I stars
Population I stars
are also known as metal rich stars. Our own sun is a Population I star and was formed about 5 billion years ago.
Geologic time periods
The geologic time scale
covers the extent of the existence of Earth, from about 4600 million years ago to the present day. It is marked by Global Boundary Stratotype Sections and Points
. Geologic time units are (in order of descending specificity) eons, eras, periods, epochs, and ages; and the corresponding chronostratigraphic
units, which measure "rock-time", are eonothems, erathems, systems, series, and stages.
The second and third timelines are each subsections of their preceding timeline as indicated by asterisks. The Cenozoic is sometimes divided into the Quaternary and Tertiary periods, although their use is no longer official.