What is the geographic luck theory?

The geographic luck theory is a theory developed by Jared Diamond to explain why European conquest of the Americas was so successful.

In a nutshell, he believes that the difference in technology, civilizations, and the like are not determined by biological traits or ingenuity, but instead by simple geological advantages an area has over another which allowed civilizations that resided on them to advance faster than civilizations living elsewhere.

Among these simple differences are: different species of animals (that could be domesticated); different crops with varying degrees of nutrition, hardiness, etc.; and climate.