From iA wiki
Software tools used for social interaction, usually with a "friend"-based system that prevents just anyone from messaging you. They can be anonymous or personal. They can be a program you download and install or Web-based and operated through a browser.
IRC is separate from Instant Messenger but as the interface has become more and more IRC-like, the term has hybridized in some ways. One major difference: generally, IM systems require specifically accepting any new person while IRC has no limits to who can message you, offering only the client-based
/ignore (or on some IRC networks the server-based
/silence) command if you don't wish to speak with them.
Most instant messaging systems are formed in a traditional client/server scheme. Some purely peer-to-peer chat systems exist but are still rare. As running IM servers can be expensive, many services are trying to become more peer-to-peer, or include adware, or use their network for marketing purposes, brand recognition, or karma.
A list of Instant Messenger Clients and Tools
- Personal - Choice of chat client can often depend on whether the people you currently know are using that client. Contact your friends and find out which tool they use. Some of the most popular (but not necessarily the best) are:
- Jabber - semi-decentralized, open-source IM system supporting SSL, GPG and other IM networks.
- Anonymous - Almost any chat tool available can be fairly anonymous to other members of the chat room so long as you don't put your real name. IRC - Internet Relay Chat is fairly anonymous because there are so many different networks and you do not need to register yourself.
- Retroshare serverless anonymous encrypting Messenger
- OSCAR (AIM and ICQ)
- Gadu-Gadu - a Polish chat system
- Zephyr - MIT's messaging protocol
- MSN Messenger
- SILC IRC philosophy but with encryption all around
- Yahoo Messenger
- Yeemp A largely decentralized, encrypted protocol.
Note about syntax of IM:
- An "Instant Messenger" is a piece of software designed to connect one person to another, allowing them to chat via typing.
- IM = "Instant Messenger", but while it sends "Instant Messages" is not called an "Instant Messager".