ITunes

iTunes is a free computer programme that allows for the storage and playback of digital media on one's personal computing device. It is available on several different platforms and on devices ranging from iPhones to iPads to full-sized desktop computers. Additionally, people using iTunes on several different devices can automatically sync the content in their possession, such that they are able to play their media on all the devices they own.

The term is also used colloquially to describe the iTunes Store, a digital download service offered by. Some things on this service are free, while most are for purchase. Apple's business model in making iTunes available for free is the expectation that, at some point, the consumer will eventually buy materials in the iTunes Store. An adjunct to the iTunes Store is the App Store, a similar service that distributes applications. Purchases from both aspects of the digital storefront are nevertheless managed by the iTunes program on one's personal electronic devices.

iTunes and Doctor Who
Doctor Who's involvement with the iTunes has been both significant and broad. The British Broadcasting Corporation has made much of the Doctor Who library available for sale. A significant measure of Doctor Who's popularity in the United States, for example, rests on the notion that it sits high atop the rankings of television shows sold through season passes in the US iTunes store. Doctor Who audio has also traditionally sold well. For the week ending 11 October 2013, for instance, the Tenth Doctor adventure Pest Control was in the top 10 of the Australian store. Indeed, material from BBC Audio — and now its successor, AudioGO — has long been on the iTunes store, making missing episode audio broadly available around the globe since the mid-2000s. Additionally, Doctor Who games began showing up in the early 2010s, such as The Mazes of Time.

Region specificity
A significant element of the iTunes and App Stores is that material can be sold by global region. Thus, it is possible that content be made available only in the United States or British iTunes Store, but not in both. In the Doctor Who fan community, this has sometimes led to frustration, as some products have been released in the US and UK, but not in Australia and New Zealand. A recent complaint heard from New Zealand was that the recovered episodes of The Enemy of the World and The Web of Fear were not put in the New Zealand iTunes Store concurrent with their sale in the United States and Britain.