Instant messaging (IM) and chat are technologies that make the possibility of real-time text-based communication between two or more participants over the internet or some form of internal network/intranet. It is important to understand that what separates chat and instant messaging from technologies such as e-mail is the apparent synchronicity of the communication by the user - Chat happens in real-time previous to your eyes. Some systems allow the sending of messages to people not at present logged on (offline messages), thus removing much of the difference between Instant Messaging and e-mail.
As many services have additional features such as: the instant receipt of acknowledgment or reply, group chatting, conference services (including voice and video), conversation logging and file transfer, those functions are further than the scope of this article.
IM allows effectual and efficient communication, featuring immediate receiving of acknowledgment or reply. In certain cases Instant Messaging involves extra features, which make it still more popular, i.e. to observe the other party, e.g. by using web-cams, or to talk directly for free over the Internet.