The iPod, the device that loaned its name to podcasts and helped end the reign of the CD, is being discontinued a little over 20 years after it was first unveiled. Apple announced on Tuesday that the last remaining model – the iPod touch – will only be available while stocks last. The portable music player paved the way for Apple to enter the smartphone market with the iPhone after its launch in 2001 with an intuitive click wheel and iconic white earphones. It also enabled Apple to expand its business beyond computers and push the music industry into more digital arenas. Apple had already disc…