The iTunes Store is an online media store that you can access via a computer, iOS smartphone/tablet, or Apple TV. The store offers a wide variety of content, including music, movies, TV shows, books, podcasts, and apps for your iOS devices. If you use the iTunes media manager software on your computer, you'll find a direct link to the iTunes Store along the left-side toolbar; iOS devices like iPads and iPhones contain preloaded apps that link you to iTunes and the App Store. The iTunes Store is a pay-per-use service, meaning that you pay a one-time fee for each song, album, movie, or TV show that you acquire (podcasts are generally free). This is different from subscription services like Netflix, Hulu Plus, and Rhapsody, which require a monthly fee to access an unlimited amount of content.
On the music side, the iTunes Store generally allows you to purchase individual songs or complete albums. Songs usually cost between $0.69 and $1.29, while the price of albums varies a great deal, depending on artist, release date, etc. In the early days, all songs were offered in an encrypted AAC file format, at a resolution of 128 kilobits per second. Since 2009, however, all songs are now offered in the iTunes Plus format, an unencrypted form of AAC at 256 kbps. Because the files are unencrypted, you can play them on any device that supports playback of the AAC format. The iTunes Store does not sell full- or high-resolution music tracks.
On the video side, TV shows are available for purchase only, not rental. Once you buy an episode, it will remain in your iTunes content library until you delete it. Individual episodes generally cost $2.99 for HD quality and $1.99 for SD quality. You can also subscribe to the season pass for a TV show at a slightly discounted rate. Movies are available for either rent or purchase. Rented titles will stay in your iTunes library for 30 days; once you begin playback of a selected title, you have 24 hours to watch it. Then, it will disappear from your library. Purchased titles remain in your content library until you delete them. Pay-per-use services like iTunes and VUDU generally receive new home-video releases around the same time they arrive on DVD, while subscription services like Netflix often have to wait a much longer time to receive these titles. Sometimes a title will be available for purchase before it is available for rent. For new releases, rented titles usually cost $3.99 to $4.99, while purchased films generally cost $14.99 to $19.99 (depending on quality, see below)
Video titles are offered at two quality levels: SD and HD. HD content is offered in 720p or 1080p, depending on how you set up iTunes. If your computer or iOS device supports 1080p playback, then you should go into iTunes preferences and go to the Store section: Where it says "When downloading high-def videos, prefer," select 1080p. If your device doesn't support 1080p, select 720p instead. On the audio side, many new titles come with a Dolby Digital 5.1 soundtrack, but some titles may be offered only in PCM stereo.
The iTunes Store allows you to download content (even rented titles) to compatible devices so that you can play it back without an Internet connection. (Services like Netflix are streaming only, so you must have a constant network connection to watch content.) iTunes will often allow you to begin watching a movie before the download is complete; you might be able to watch the movie almost instantly, or you might have to wait a while, depending on the speed of your Internet connection. The average HD-quality film has a file size of 3.5 GB or more.
Apple offers a service called iCloud through which you can store all of your media content in a digital locker. Apple automatically stores a copy of every title you purchase through the iTunes Store in your free iCloud account, and you also have the option to add other music, movies, photos, calendars, etc. You can stream your iCloud-stored content to all of your compatible Apple products, and you can directly download any iCloud-based file to any compatible device. A basic iCloud account is free and provides 5 GB of storage (purchased iTunes content and photos stored on Photostream do not count against that 5 GB), or you can add 10 GB for $20/year, 20 GB for $40/year, or 50 GB for $100/year.