The iTunes Store is a software-based online digital media store operated by Apple Inc. that opened on April 28, 2003, as a result of Steve Jobs's push to open a digital marketplace for music. It is the largest music vendor in the world.

 

As of June 2013, the iTunes Store possessed 575 million active user accounts, and served over 315 million mobile devices. As of April 2020, iTunes offers 60 million songs, 2.2 million apps, 25,000 TV shows, and 65,000 films. When it opened, it was the only legal digital catalog of music to offer songs from all five major record labels. 

The iTunes Store is available on most Apple devices, including the Mac (inside the Music app), the iPhone, the iPad, the iPod touch, and the Apple TV, as well as on Windows (inside iTunes). Video purchases from the iTunes Store are viewable on the Apple TV app on Roku and Amazon Fire TV devices and certain smart televisions. 

According to en.wikipedia