Netiquette (Internet Etiquette)
Every few months a plague descends on Usenet called the spelling flame. It starts out when someone posts an article correcting the spelling or grammar in some article. The immediate result seems to be for everyone on the net to turn into a 6th grade English teacher and pick apart each other's postings for a few weeks. This is not productive and tends to cause people who used to be friends to get angry with each other.
- Chuq Von Rospach, Gene Spafford, Mark Moraes; A Primer on How to Work With the Usenet Community, 1983-1995.
"Netiquette" stands for "Internet Etiquette", and refers to the set of practices developed over the years to make the Internet experience pleasant for everyone. Like other forms of etiquette, netiquette is primarily concerned with matters of courtesy in communications. The following sections provide more information.
Netiquette Basics
Help the newbies
Research before asking
Remember emotion
People aren't organizations
Netiquette Of Sending:
Be brief
Use white space
Use descriptive subject lines
Stay on-topic
Be careful sending attachments
Copy the minimum number of people
Include your email address
Respect non-commercial spaces
Avoid flaming
Netiquette Of Replying
Replying and forwarding
Summarize for the group
Check current information before replying
Reference past communications
Acknowledge important communications
Netiquette Of Confidentiality
Don't publicize other's email addresses
Never send what you don't read
Remember archiving
Respect copyright
More Netiquette Information.

THE CORE RULES OF NETIQUETTE
The Core Rules of Netiquette are excerpted from the book Netiquette by Virginia Shea. Click on each rule for elaboration.
Introduction
Rule 1: Remember the Human
Rule 2: Adhere to the same standards of behavior online that you follow in real life
Rule 3: Know where you are in cyberspace
Rule 4: Respect other people's time and bandwidth
Rule 5: Make yourself look good online
Rule 6: Share expert knowledge
Rule 7: Help keep flame wars under control
Rule 8: Respect other people's privacy
Rule 9: Don't abuse your power
Rule 10: Be forgiving of other people's mistakes