The next iPad features a display resolution of 2048 x 1536. This is four times the number of pixels on the original iPad and iPad 2.
Apple calls this the Retina display because it features 264 pixels per inch (ppi). This density means that individual pixels can't be distinguished at 15 inches away.
The number of pixels on the iPad Retina display totals 3.1 million, which is one million more pixels than a 1080 HD display. iOS will automatically increase the resolution of existing non-Retina iPad apps to accomodate the improved hardware.