The maximum rate of world oil production. With the exception of a few anamolies due to unusual
geology and other various factors, every oil field follows a pattern in its production where oil production increase as it's first developed, reaches a maximum point or
plateaus at a lesser artifical maximum, and then declines from then
onward. When this maximum production is reached on a worldwide level, that is
peak oil.
The real interests of this are of course the effects decreasing oil production will have on the world economy if the mainstream is not converted to a different alternative energy infastructure beforehand. Since the world
economy's infastructure is so heavily dependent on oil, the price of everything else will go up as well as oil (which will
skyrocket as the price of oil has been kept at an artifical low for the last several decades by excessive supply), and the economy will come to a crashing and spectacular finish as the world is thrown into super depression and the social instability that entails. More dire predicts based on the
reliance of modern agriculture on cheap oil speak of a massive dieoff as the world's food production, some claim, will no longer be able to support a world population above
4 billion.
Armed with such predictions, many peak oilists are strong advocates of alternative energy in the hopes these apocalyptic scenarios don't come to pass.