Soundcloud is an online community which unleashes sounds from clouds. 

In August of 2007 Alexander Ljung and Eric Wahlforss founded Soundcloud in Stockholm with the intent to "unleash the sound creator in everyone" (Wahlforss himself is a producer and DJ. Afficiandos of Jazzanova's Sonar Kollektiv label may recognize him as "forss"). About a year later their project launced. At the time, MySpace was the best option for musicians looking to be self-promoters. Within months of launching, SoundCloud eclipsed the aging MySpace and moved its HQ to Berlin.

There are lot of permutations of electronica on SoundCloud. But there are also lots and lots of other forms of music.

SoundCloud currently has over 20 million users with a growth rate of over 1.5 million users per month.

A SoundCloud account is free, which gives all users their own unique URL to which they may upload their own audio. An account is not needed to download or stream content, though one is needed in order to leave a comment on a track. Comments may be left at specific points in time on an audio track, which is displayed graphically as a waveform. 

SoundCloud has an API that allows other applications or smartphones to upload or download audio content. A current version of FLASH is necessary to run the program from a laptop or desktop. The SoundCloud API has also been integrated into a number of different software used for audio production, making it easier for DJs and producers to upload content.

SoundCloud has recently revamped their site into Next SoundCloud, with a more slick, streamlined interface. There are several new features such as autopausing (if you click one track while listening to another one, https://soundcloud.com/ the first one automatically pauses) and the ability to listen to a file while navigating elsewhere on the site.

SoundCloud also offers a number of unique features for those who wish to pay a subscription fee. There are currently four levels for paid subscribers:


Lite for 29 Euro/year or ~42USD

Solo for 9 Euro/month or 79 Euro/year or ~116 USD 

Pro for 29 Euro/month or 250 Euro/year or ~370 USD 

Pro Plus for 59 Euro/month or 500 Euro/year or ~740 USD

A free account allows any user to upload 120 minutes of audio and the Lite account doubles that. The Solo account grants 12 hours while the Pro account triples that. There is no upper limit for the Pro Plus. The paid subscription options also allows account holders to find out other information such as where people are downloading their music.

It is also possible to sell music via iTunes using SoundCloud.  

Although SoundCloud was created as a collaborative tool, some users do upload unadulterated recordings from well-known musicians. It happens. SoundCloud's will gladly remove such content but only if the party reporting an instance of piracy is (or represents) the copyright holder in question. Piracy is rare on this site due to the relatively short allotment of upload time granted to each user. But, if you look for something specific, you may find it. For example, you could search SoundCloud for "ESCM" hoping to hear some remixes of BT's progressive house classic. The first hit is of a user sitting on that handle with no content, the second is an upload of the popular single, but the other search results are either original remixes or reinterprations, or other content that is of a similar style or wholly unrelated. 

SoundCloud allows users to "follow" other users (without reciprocation) and send messages or leave public comments on tracks. There are also groups available for those looking to collaborate.

A few months prior to the release of SoundCloud, a similar site called Bandcamp appeared. For a more detailed comparision between SoundCloud and Bandcamp, check out this blog post. The basic gist of that link is that Bandcamp is preferrable for established groups of musicians as 1) Bandcamp lacks the upload limits of SoundCloud and 2) Bandcamp only charges after a musicians has reached a certain level of sales.

Also, the blog post linked to above was written prior to SoundCloud's changes as of 12/2012. A few weeks after new changes to the SoundCloud site became mandatory, many heavy users began complaining about the site "recommending" who they should follow, shrinking the size of icons in comments, having the site favor those with mobile devices, making high-bandwidth connections a requirement for uploading, and generally becoming more commercial (in the interests of the site itself, not the sound creators). For a full list of grievances against SoundCloud, check out The Revolution will be audiovised.

The aforementioned grievances aside, if you prefer to discover new music on your own or are interested in having your music reach a wider audience or wish to collaborate over great distances or represent a label or a radio station, SoundCloud is a good choice.

In February of 2013, the SoundCloud team has begun a project called AudioBiography, in which they invite every user to record a sound which describes who they are and why they seek to make the sorts of sounds which they do. That collaborative effort is a continuation of the previous experiment of Sound School, which was a group account made with the intent for sharing knowledge and techniques for making sounds.

website

Registry of E2ers in the cloud

E2 podcasts

ResidentAdvisor interview with one of the founders of SoundCloud