IRC was at, one point, one of that largest and most used ‘parts’ of the internet, mainly during the 90’s. Simply defined, IRC is chatroom; a very primitive one at that. Basically you would type messages and send them into the main chatroom, or ‘channel’, and communicate with others.
In the early days of IRC you would have to download an IRC client in order to access an IRC channel. However now days, at least in Google Chrome, the browser has a client built into it making a third party client largely redundant. Anybody with access to the internet could hop onto one of these IRC channels and talk to anyone of the people connected to it. This allowed people from across the globe to communicate with one another without ever actually meeting.
Although IRC was initially invented in 1988 it never really exploded until 1991 when users were suing the IRC channels to get up-to-date information about the invasion of Kuwait by Iraq. The IRC channel that was linked into the country stayed active up to a week after the television and radio broadcast networks were taken down. An archived copy of the IRC chat can be found here.
Now days IRC is not used as much anymore due to the rise of other, more user friendly, instant messaging services; most notably MSN Messenger (now known as Windows Live messenger), Yahoo Messenger and AOL Messenger. IRC now is mostly seen as a low tech way of communicating but is still widely used in some online communities.
One notable mention should be the use of IRC by hacker groups as well as the hacktivist group, Anonymous. IRC channels are widely favoured by these groups for their ability to handle large groups of people as well as giving the users the option to appear anonymously. Anonymous especially used IRC channels to organise wide spread DDOS attacks in 2010.
IRC channels lead the way for modern instant messaging programs. It could be argued that without the existence of IRC channels; MSN, Yahoo, AOL Messenger and the like would not have come to fruition. IRC allowed the sharing of information in real time to people all over the world.
Internet relay chat (IRC) history 1996, viewed 6 August 2012
Stenberg, D 2011. History of IRC (Internet relay chat), viewed 6 August 2012
Correll, S 2010. ‘Tis the season of DDOS – wikileaks edition, viewed 6 August 2012