YouTube is an American video-sharing website headquartered in San Bruno, California.

The service was created by three former PayPal employees—Chad Hurley, Steve Chen, and Jawed Karim—in February 2005.

Google bought the site in November 2006 for US$1.65 billion; YouTube now operates as one of Google's subsidiaries.

The site allows users to upload, view, rate, share, add to favorites, report and comment on videos, subscribe to other users, and it makes use of WebM, H.264/MPEG-4 AVC, and Adobe Flash Video technology to display a wide variety of user-generated and corporate media videos.

Available content includes video clips, TV show clips, music videos, short and documentary films, audio recordings, movie trailers and other content such as video blogging, short original videos, and educational videos.

MPEG-1 and/or MPEG-2 Audio Layer III, more commonly referred to as MP3 (or mp3), is an audio coding format for digital audio which uses a form of lossy data compression, which are data encoding methods that use inexact approximations and partial data discarding to reduce file sizes significantly, typically by a factor of 10, in comparison with a CD, yet still sound like the original uncompressed audio to most listeners.

Compared to CD quality digital audio, MP3 compression commonly achieves 75 to 95% reduction in size.

MP3 files are thus 1/4 to 1/20 the size of the original digital audio stream.

This is important for both transmission and storage concerns.

The basis for such comparison is the CD digital audio format which requires 1411200 bit/s.

A commonly used MP3 encoding setting is CBR 128 kbit/s resulting in file size 1/11 (=9% or 91% compression) of the original CD-quality file.

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.

Free software, freedom-respecting software, or software libre is computer software distributed under terms that allow the software users to run the software for any purpose as well as to study, change, and distribute the software and any adapted versions.

Free software is a matter of liberty, not price: users, individually or collectively, are free to do what they want with it, including the freedom to redistribute the software free of charge, or to sell it, or charge for related services such as support or warranty for profit.

In telecommunications and computing, bit rate (sometimes written bitrate or as a variable R) is the number of bits that are conveyed or processed per unit of time.