This article is from the Sacramento FAQ, by David F. Prenatt, Jr. with numerous contributions by others.
Communication between individuals on the Internet usually takes place
through the institutions of e-mail and the USENET newsgroups. These
are the most straightforward and easy to use Internet applications.
Live time conversations also take place with the Internet Relay Chat
(IRC); the World Wide Web provides access to multimedia communication.
I hesitate to mention the highly intrusive Internet communication
software "talk/ytalk," but for those of you who want more information
on how to interrupt people with a talk request, contact David T.
Witkowski (<mailto:email@example.com >; readers with a web
browser may visit David T. Witkowski's Ytalk Primer on the World Wide
Web (<http://www.ece.ucdavis.edu/~witkowsk/ytalk.html >).
10.2.2.1) Are there any rules for using e-mail and the USENET newsgroups.
In most instances, yes. Most ISPs impose regulations for e-mail and
the USENET. There are also informal rules of conduct that are
enforced by the Internet community (fondly referred to as
"netiquette"). For further information on official regulations on e-
mail and the USENET, contact your ISP. As for netiquette, use your
own good judgment.
10.2.2.2) What is the difference between e-mail and the USENET newsgroups?
The primary difference between e-mail and the USENET is privacy.
However, neither e-mail or the USENET are confidential. An e-mail
message is directed to a particular individual or group of
individuals; a USENET article is directed to anyone who has access to
the newsgroup where the article is posted. If you want to conduct
confidential communications over the Internet, check out an encryption
program such as PGP ("Pretty Good Privacy").
PGP has a public domain version that is available free of charge
to anyone who is using it for non-commercial purposes. It has
thwarted virtually every attempt that people have made to crack it.
What makes PGP unique is that the key that encrypts your mail (i.e.,
your "public key") is distinct and separate from the key that
unscrambles it (i.e., your "private key"). Unless you tell someone
your private PGP key or someone guesses it (which could take thousands
of years of computer time) or discovers it by eavesdropping, no one
can read your PGP encrypted mail.