What is big history?

Big history provides an overview of all of history, from the beginning of the universe until life on Earth today, in ways that are easy to understand by all educated persons. In doing so, big history also offers the best possible knowledge for making projections of the future. Like all academic endeavors, big history is entirely based on empirical evidence and scholarly interpretations.
Big history is about increasing and decreasing complexity throughout the history of the universe. It is thought that about 13.8 billions years ago, the universe came into being as a very hot and very dense undifferentiated combination of matter and energy. Over time, it cooled down and expanded, leading to a separation of energy and simple forms of matter, mostly hydrogen and helium. Out of this matter, countless galaxies and stars emerged, surrounded by increasingly large, cold, and empty interstellar and intergalactic space.
In big stars, heavier chemical elements were forged in their cores or during the gigantic explosions called supernovas, that signal the end of the lives of these huge stars. Dispersed into the galaxy and mixed with hydrogen and helium clouds, these heavier chemical elements were incorporated into new processes of star formation. This allowed planets like Earth to emerge, which consist mostly of these heavier chemical elements. Our solar system is thought to have formed in such a way about 4.6 billion years ago.
Over a period of 4.5 billion years, our planet evolved from a hot and relatively simple celestial body to the structure it has today. Earth has a hot, partially molten core mostly consisting of iron and nickel, which causes the magnetic field that shields us from harmful cosmic radiation and provides orientation with the aid of compasses.
Outside the core, the Earthís mantle consists of heavy rocks that slowly move much like water in a boiling pot, but much more sluggishly. These movements drive changes on the Earthís surface, jointly called plate tectonics, leading to mountain formation, earthquakes, volcanism and ocean spreading, all of which ceaselessly changes Earthís geography. Erosion caused by wind, rain, and microorganisms (and now also humans) counteracts the effects of mountain building.
On our planetís surface, life emerged (probably) and developed (certainly) in continuous interaction with its environment. While many life forms remained small and relatively simple, some of them became increasingly complex. Eventually this led to the emergence of humans who, over a period of about 10,000 orbits of our planet around the sun, went from making a living as gatherers, hunters, and fishers to become what we are now.
If you want to know more about how all of this happened, why not read the book?
International Big History Association
Un. of Amsterdam big history
Cosmic Evolution
Big History Project
Book: Teaching Big History
Bill Bryson: Short History of Nearly Everything
Other useful stuff on the web
Other big history
How to use the book
Course models
Learning goals and objectives
Teaching tools
Assignments (little big histories)
Answers to FAQs by students
Questions by students and teachers that go beyond the book
Examination models
Teaching big history