The Barnes & Noble Nook (styled nook or NOOK) is a brand of e-readers developed by American book retailer Barnes & Noble, based on the Android platform. The original device was announced in the U. S. in October 2009, and was released the next month. The original Nook had a six-inch E-paper display and a separate, smaller color touchscreen that serves as the primary input device and was capable of Wi-Fi and AT&T 3G wireless connectivity. The original nook was followed in November 2010 by a color LCD device called the Nook Color, in June 2011 by the Nook Simple Touch, and in November 2011 and February 2012 by the Nook Tablet. On April 30, 2012, Barnes & Noble entered into a partnership with Microsoft that spun off the Nook and college businesses into a subsidiary. On August 28, 2012, Barnes and Noble announced partnerships with retailers in the UK, which began offering the Nook digital products in October 2012. In December 2014, B&N purchased Microsoft's Nook shares, ending the partnership.
In November 2017, B&N announced the 3rd generation of the GlowLight e-reader. The device returned to a design more reminiscent of the original Simple Touch and dropped the IP67 certification.  The Glowlight 3 has an enhanced lighting system that provides a cool white during the day or in rooms with bright light, but then can manually or automatically switch to night mode with an orange tone for reading in dark spaces with less blue light.
I have tried a dozen of methods to convert my PDF books to EPub format; Most of the time, the result is frustrating. Numbering, page setup, footnotes, headers, pictures all get messy in the result.