Tumblr is a microblogging and social networking website founded by David Karp in 2007, and owned by Yahoo! since 2013.

The service allows users to post multimedia and other content to a short-form blog.

Users can follow other users' blogs.

Bloggers can also make their blogs private.

For bloggers, many of the website's features are accessed from a "dashboard" interface.

SoundCloud is an online audio distribution platform based in Berlin, Germany, that enables its users to upload, record, promote, and share their originally-created sounds.

SoundCloud's content is evenly split between music and other audio.

Founders Alexander Ljung and Eric Wahlforss are the chief executive officer (CEO) and chief technical officer (CTO), respectively.

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.

Tistory is a South Korean blog-publishing service that allows private or multi-user blogs.

It was first started by 'Tatter and Company', a blogging platform developing company who developed the software 'Tattertools',

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.