What iPod was the first released?

On October 23rd, 2001, Apple released the first iPod, simply called "iPod". It was 5 gigs and about the size of a deck of cards. It ran $599, and while people bawked at the price, it was an instant hit in the marketplace. Later, as the device was revised and improved, similar devices were released, now dubbed "generations". So, to answer your question, the first iPod is known today as a 1G or "First Generation" iPod.