Although the 21st century has just begun, there have been many scientific inventions during the first decade of it, among which iPod is no doubt one of the greatest. iPod is a portable media player designed and marketed by Apple and launched on October 23, 2001. From then on, iPod has been the best digital music player in the world. iPod is one of the greatest inventions in the 21st century for many reason. First and foremost, the birth of iPod marked the beginning of the MP3 era. iPod, together with iTunes, another product of Apple, made a revolutionary change to the music player industry. At the time before, the main devises to store music files are CDs, thus the market was occupied by CD players. However, the invention of iPod put an end to the domination of CD players. It is more convenient to use an iPod than a CD player. As iPod has a hard disk to store music files, we need only to download music to our iPod rather than buy lots of CDs and constantly change one to another. Furthermore, as with many other digital music players, iPod can also serve as external data storage devices. Last but not least, enhancements to the iPod over successive years have been astounding in terms of features and consumer benefits. Now, iPod is more than a music player. Video games are playable on various versions of iPods. We can also surf the Internet and make Internet phone calls via iPod. But there are still some problems. The batteries of iPod last only a very short time and are easily worn out. In addition, iPods have been criticized for their short life-span and fragile hard drives. Seeing these shortcomings, Apple has made efforts to perfect iPod. Though having some defects, iPod has been popular since it was invented. With the improvement made by Apple, I believe that iPod will be better and better and live up to its position as one of the greatest invention in the 21st century.