Basically, it’s a small program that tells you if your friends (who also run the program) are online and active, and then you can type messages to them that pop up instantly on their screen. It’s like halfway between talking with somebody, and sending email. More instant than email, but not as instant as talking.
The first step might be to talk to people you might want to chat with via IM, like friends and family, and see which system they use. The big ones are AOL IM (AIM), Microsoft MSN, and Yahoo.
If they are all on the same system (unlikely, but possible), you should go with that system. If not, you can use a program like GAIM to connect to multiple systems at once.
silenius has basically covered the last question for the two most popular services out there. Now for the first two questions:
Basically, you download a piece of software for your computer. While you’re connected to the internet, you can then use this software to sign in to a central server somewhere. People with the same software can then see that you are online, and can send you messages that will appear instantaneously on your own machine. You can then carry on protracted conversations this way.
As always, Wikipedia explains things in painstaking detail, if you’re interested.
If you think you might want to IM fellow Dopers, look under their “Location” for a little symbol. The little yellow man shows that I have AIM. A red “Y!” means Yahoo. A little blue bust means MSN.
Haven’t seen either of those movies. Most of the time with instant messaging you don’t see the actual typing, but your message is sent when you hit enter, and pops up immediately on the messagee’s screen. ICQ at least has a format where you can see each other typing too, but that’s not the ordinary operational mode.
If I may offer an opnion – get Yahoo, not AIM – AIM comes with all sorts of miscellaneous crap that you then have to take off your machine a program at a time.
Another all-in-one alternative is Miranda IM. It can handle ICQ, IRC, MSN and Jabber. I use it for MSN, primarily, because it’s bare-bones. No software bloat whatsoever. It actually looks a lot like the original versions of ICQ (which I still maintain was a better system, at least back before it got all popular and fat!)
IM is halfway between email and something called “IRC” (Internet Relay Chat).
The difference?
With email, you compose a message and send it. Later, the recipient (or recipients–there can be more than one) opens it and reads it. Sender and receiver do not need to be online at the same time.
IRC is something where you and the recipient (or recipients) are online at the same time. You start an IRC program, and it lets you know whether your contacts are online, and lets them know that you are online. (You join a “channel”, like a conference call, that gives you a list of whoever else is present.)
When you type in IRC, everyone else sees every keystroke you make, including all errors, as you type. It is very like a phone call or conference call, in text; there is no facility to edit or review your message (to correct errors or change your mind) before sending. Every line of text you type is interleaved with those that others type.
IM combines the immediate connectivity of IRC with the chance for review of email.
You’re still online with your contacts; the IM program still lets them know you’re there and vice versa. The lines of text you type still appear interleaved with what others type. But you get a chance to create and check your entire message before sending it. I honestly think this is why IM is so much more popular than IRC.
Yahoo does have one advantage. If you send an IM to a person offline, when they sign on, it will pop up for them, so it’s like you’ve sent an email via IM.