At the end of 2016, how many different generations of iPads had Apple released?

SIX

With the release of the iPad Air 2 In October 2014, Apple began selling the sixth generation of its signature tablet. While the popular tablets first made their debut in 2010, the core concept dates all the way back to the Newton MessagePad 100, Apple’s first “tablet” released in 1993. The Newton failed to take off, and it would be more than a decade before Apple would again venture into making a tablet. Source: Wired, New Atlas