Listservs can be public or private. Generally, the people all share what Richard Vonnegut called a "karass" - they all have something in common, whether it's bicycling, working at the same place, or trying to determine the number of microprocessors that can dance on the head of a pin.

At any rate, a listserv is a great way for people with a common interest to communicate about it. If you belonged to a biology listserv, you were probably exchanging e-mail faster than your disk drive could spin when the news about Dolly, the cloned sheep, came out.

Listservs are tres valuable for beat reporters who write about certain subjects. It's a great idea, say, to get on government-related listservs if you write about government or politics, medical listservs if you're a medical writer, and so forth. Just by checking in once or twice a day, you might hear about some new development, and you can always e-mail technical or other questions to the group.

To get on a private listserv, you have to be added by someone who is on the list. In this case, your best bet is probably e-mailing someone who is on the list; of course, you have to find out about the listserv, and the e-mail of someone in the gang, before you can take this step.

To get on a public listserv, generally, you send e-mail to the e-mail address with a certain specified message in the body, and presto! you're on the list. Unless you're a real spam aficionado (spam being the online equivalent of junk mail), it's not a bad to be selective about the lists you join. Just a thought!

For a list of listservs to which you might wish to belong, check out Liszt.