The first iPad. No camera, no multitasking until November, and a million sold in 28 days.
Released April 3, 2010 · Discontinued March 2, 2011 · From $499 (16 GB, Wi-Fi)

Steve Jobs sat down in a leather armchair on stage on January 27, 2010 to introduce it, which was itself the argument: this was a device you used on a sofa. The reaction beforehand had been scornful. It was a big iPhone, it was a giant iPod touch, the name was the subject of a week of jokes. Then it went on sale in April and Apple sold a million in 28 days, which took half the time the original iPhone had. The A4 was Apple's first in-house system on a chip, a 9.7-inch 1024x768 IPS screen ran ten hours on a charge, and the whole thing weighed 680 grams. There was no camera at all. There was no multitasking until iOS 4.2 arrived that November. None of that stopped it, because the thing it did do, put the web and a book and a video in your hands with no fan and no keyboard in the way, had not really existed before.
Reviewers concluded the iPad could stand in for a laptop a good deal of the time, while listing what it could not do: no multitasking at launch, no camera, no USB, no Flash.
the iPad can indeed replace a laptop for most data communication, content consumption and even limited content creation, a lot of the time.
the iPad is an advance in making more-sophisticated computing possible via a simple touch interface on a slender, light device.