iTunes Store is a software-based online digital media store operated by Apple Inc. It opened on April 28, 2003, and has been the largest music vendor in the United States since April 2008, and the largest music vendor in the world since February 2010.

It offers over 35 - 40 million songs, 2.2 million apps, 25,000 TV shows, and 65,000 films as of January, 2017.

iTunes Store's revenues in the first quarter of 2011 totaled nearly US$1.4 billion; by May 28, 2014, the store had sold 35 billion songs worldwide.

MPEG-4 Part 14 or MP4 is a digital multimedia container format most commonly used to store video and audio, but can also be used to store other data such as subtitles and still images.

Like most modern container formats, it allows streaming over the Internet.

The only official filename extension for MPEG-4 Part 14 files is.mp4.

MPEG-4 Part 14 (formally ISO/IEC 14496-14:2003) is a standard specified as a part of MPEG-4.

Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression.

Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at similar bit rates.

Digital distribution (also called content delivery, online distribution, or electronic software distribution (ESD), among others) is the delivery or distribution of media content such as audio, video, software and video games.

The term is generally used to describe distribution over an online delivery medium, such as the Internet, thus bypassing physical distribution methods, such as paper, compact discs, and VHS videocassettes.

The term online distribution is typically applied to freestanding products; downloadable add-ons for other products are more commonly known as downloadable content.

With the advancement of network bandwidth capabilities, online distribution became prominent in the 21st century.

In computing, source code is any collection of computer instructions, possibly with comments, written using a human-readable programming language, usually as ordinary text.

The source code of a program is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source code.

The source code is often transformed by an assembler or compiler into binary machine code understood by the computer.

The machine code might then be stored for execution at a later time.

Alternatively, source code may be interpreted and thus immediately executed.