The Big Bang theory is the prevailing cosmological model for the earliest known periods of the universe and its subsequent large-scale evolution. It states that the Universe was in a very high density state and then expanded. If the known l...

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the world, the Blue Pl...

The Cambrian is the first geological period of the Paleozoic Era, lasting from 541 to 485 million years ago (mya) and is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by...

The Permian is a geologic period and system which extends from 299 to 252 million years ago. It is the last period of the Paleozoic Era, following the Carboniferous Period and preceding the Triassic Period of the Mesozoic Era. The concept o...

The Mesozoic era is an interval of geological time from about 252 to 66 million years ago. It is also called the age of reptiles, a phrase introduced by the 19th century paleontologist Gideon Mantell who viewed it as dominated by reptiles s...

The Cenozoic Era, meaning "new life", is the current and most recent of the three Phanerozoic geological eras, following the Mesozoic Era and covering the period from 66 million years ago to the present. The Cenozoic is also known as the...

The first species of the genus Homo, evolved in South and East Africa in the late Pliocene or early Pleistocene (2 - 2.5 million years before present) when it diverged from the Australopithecines (Australopithecines and Hominenes are collec...

The last glacial period, popularly known as the Ice Age, was the most recent glacial period within the current ice age occurring during the last years of the Pleistocene, from approximately 110,000 to 12,000 years ago. Scientists consider t...

The Neolithic Era or New Stone age, was a period in the development of human technology, beginning about 10,200 BC, according to the ASPRO chronology, in some parts of the Middle East, and later in other parts of the world and ending betwee...

The Bronze Age is a time period characterized by the use of bronze, proto-writing, and other early features of urban civilization. The Bronze Age is the second principal period of the three-age Stone-Bronze-Iron system, as proposed in mo...

The Iron Age is the period generally occurring after the Bronze Age, marked by the prevalent use of iron. The early period of the age is characterized by the widespread use of iron or steel. The adoption of these materials coincided with...

The Hellenistic period is the period of ancient Greek and eastern Mediterranean history between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire as signified by the Battle of Actium in 31 BC and the subsequen...

The Roman Empire was the post-Republican period of the ancient Roman civilisation, characterised by an autocratic form of government, headed by an Emperor, and large territorial holdings around the Mediterranean Sea in Europe, Africa, the M...

The Byzantine Empire was the predominantly Greek-speaking continuation of the eastern half of the Roman Empire during Late Antiquity and the Middle Ages. Its capital city was Constantinople (modern-day Istanbul), originally known as Byzanti...

The Middle Ages was the middle period in a schematic division of European history into three 'ages': Classical civilization, the Middle Ages, and Modern Civilization. It is commonly considered as having lasted from the end of the Western Ro...