An IRC-client is an interactive client which connect to an IRC-server and does understand the IRC protocol. Currently there exist many IRC-client for many operating systems. Some are nice graphical clients, some are text-based and many of them allowing the user to implement their own scripts. So these IRC-client's are high customizable. Because is there a feature missing then you can implement it yourself.
Important Featurs
I can't advise an IRC-client for your choice. Every client has it's own pros and cons. But if you are searching for a client then I can list some things which are necessary in my opinion:
Support for a scripting language. This is the most important feature of an IRC-client in my oppinion. Because if it has a powerful scripting API then you can implement all features you like yourself.
Highlighting by nick and keywords. This is necessary if you are using ircchannel's which have an high user-count and an high activity. In this case you can dye messages which are from a special nick or contains your nick.
Sound-highlighting by nick and keywords. This is necessary if you are using your IRC-client as an alternative to an IM. In this case you can ring a sound on messages which are from a special nick or contains your nick.
Screenshot of the IRC-client XChat. (click to enlarge)
XChat is my favorite IRC-client. It has all important features which are described above. It has a graphical UI, is compatible to all *NIX Systems and Windows, is Free Software in the sense of the GPL and supports many scripting languages, such like Perl, Python, etc. Really great IRC-client in my oppionion.
Screenshot of the text-based IRC-client Irssi. (click to enlarge)
Irssi is my favorite text-based IRC-client. It has all important features which are described above, without sound-highlighting if you are connected via SSH. It has a text-based UI, is compatible to all *NIX Systems, is ported to Mac OS X and Windows, is Free Software in the sense of the GPL and supports the scripting language Perl.
Screenshot of the MS Windows IRC-client mIRC. (click to enlarge)
mIRC is a well known Windows IRC-client. It is shareware and has very many features, including the important features listed above. mIRC has a graphical UI and a scripting language to implement your own features. If you are using an IRC-client at the first time of your life then mIRC can confuse you a little bit by reason of the big feature list.
PJIRC: Is an Java-applet which can be included into an HTML file. Very useful on website's. An example is at irc.dj-l.de if you are using the Java version.
CGI:IRC: Is an server-side's CGI script which can be included into an HTML file. Very useful on website's. An example is at irc.dj-l.de if you are using the CGI:IRC version. The pros are:
The Java Virtual Machine is not required at the client side.
You can chat through a proxy server (from your companies workstation ).
irc.dj-l.de
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