This is how I see peak oil:
Peak oil means that we won't be able to extract oil from the ground at a faster rate and coincides roughly when we have used up about half of the oil that exists (or at least that we have access to with our technology). It does not mean that we have run out of oil. In order to grow economically, the world needs to use more energy and therefore it needs to extract more oil from the ground every year. When peak oil hits, we won't be able to extract oil at a faster rate and therefore our economies won't be able to grow. This has wide implications, the price of oil will get out of hand, we won't be able to afford to drive to work, food will be too expensive and countless other repurcussions. Peak oil is a scientific fact, it happened in the US in the 1970s and the US has not produced oil at a faster rate than it did in the 70s. The argument is when will the world hit peak oil.
Some analysts think it will be by 2009, others think it has already hit and others think it will be a long time from now. It was reported that
OPEC has a spare 2 million barrels per day though and the world is expected to use that by next winter.