Recorded sound is nothing new, of course, but in the early 2000s, people first started to experiment with episodic audio shows, pushing out new installments to their subscribers on a set schedule. This trend was related not only to the rise of the iPod, but also to the emergence of the MP3 format a few years earlier. MP3 was the first file type to compress high-quality audio into a size small enough to work with the era's limited internet speeds. Nowadays, we don't think anything of downloading huge 4K movies over the web, but at the start of the 2000s, internet connections were a lot slower. So the small file sizes of MP3s let you download podcasts in this format in minutes rather than hours.