[Introduction] [What
Makes Email Different?] [Context]
[Format] [Page
Layout] [Intonation]
[Gestures] [Status]
[Formality] [Greetings
and Signatures] [Summary]
[Appendix A: Acronyms and Jargon]
[Appendix B: Domain Names]
[Appendix C: Bibliography]
A Beginner's Guide to Effective Email
Domain Names
Kaitlin Duck Sherwood
How To Read A Domain
The domain name is the thing that comes after the at sign (@) in an
email address, like aol.com or arc.nasa.gov. The domain
names have different words, separated by periods, that indicate different
levels of organization. The size of the organization increases as
you go left to right. The domain arc.nasa.gov, for example,
is for Ames Research Center, which is part of NASA, which is one of
many U.S. government entities.
If I wave my hands and simplify just a little bit, the left-most
word is the name of the actual computer that handles the mail. Small
organizations might only have one computer that does everything;
larger organizations might have multiple computers. For example,
Ames Research Center email addresses currently all go through mail.arc.nasa.gov.
If you get email from someone, and there is no at sign (@), then
that probably means they have the exact same domain as you. For
example, if pat@bogusname.com sends email to chris@bogusname.com,
Chris might see only pat in the return address field.
If there seems to be something missing from the domain name, then
your correspondent may share some domain information. For example,
if pat@uno.bogusname.com sends email to chris@dos.bogusname.com,
Chris might see only pat@uno in the return address field.
Three-Letter Top-Level Domains
The last word, also called the top-level domain, in a domain gives
a clue to your affiliation. In theory, this is what three-letter Top-Level
Domains (TLDs) mean:
| TLD |
Meaning |
Examples |
| .com |
Commercial business, a company |
ibm.com, att.com, ford.com |
| .net |
Network provider, Internet Service Provider |
webtv.net |
| .gov |
U.S. governmental agency |
whitehouse.gov, nasa.gov |
| .edu |
U.S. educational institution |
uiuc.edu, stanford.edu |
| .org |
Non-profit institution |
redcross.org, sfopera.org |
| .mil |
U.S. military |
army.mil |
| .int |
International |
itu.int |
The three-letter top-level domains (except for int) were
once exclusively U.S. domains. They are still heavily U.S.-centric.
Two-Letter Top-Level Domains
If there is a two-letter top-level domain, that is a country code.
Here are some examples:
| TLD |
Country |
Examples |
| us |
United States |
city.palo-alto.ca.us, washington.k12.ia.us |
| uk |
United Kingdom |
cam.ac.uk, tvr.co.uk |
| my |
Malaysia |
parlimen.gov.my, jaring.my |
| de |
Germany (Deutschland) |
sgi.de |
| jp |
Japan |
www.hitachi.co.jp, www.nihon-u.ac.jp |
| to |
Tonga |
netsurf.to
|
| tv |
Tuvalu |
internet.tv |
An exhaustive list of country codes is at
http://www.ics.uci.edu/pub/websoft/wwwstat/country-codes.txt
.
Further Clues
Countries, especially the ones that are well-connected to the Internet,
frequently have some meaningful structure in the next-to-last word
in their domains. For example, ac is short for "academic" in
the United Kingdom, New Zealand, and Japan. Oxford University, for
example, is ox.ac.uk.
Universities in Europe frequently have the word "uni" in their
domains somewhere, short for "university". Australia uses edu
for its universities, as in usyd.edu.au.
Commercial entities frequently have co in the next-to-last
word in their domain. For example, Hitachi Japan is at hitachi.co.jp.
United States two-letter domains usually have the two-letter state
or territory abbreviation right before the .us. For example,
the city of Palo Alto in California has the domain city.palo-alto.ca.us.
(Remember that the scope increases as you go left to right:
palo-alto.us.ca would be in Canada if it existed!) U.S. State
and territory codes can be found at
http://www.usps.gov/cpim/ftp/pubs/201html/addrpack.htm#abbr
.
Children's schools in the United States frequently have the word
k12 in them. (This is short for "Kindergarten through 12th
grade", the U.S. terms for schools for students nominally ages 5-18.)
Community colleges frequently have cc as the next-to-last
word in the domain.
Canada also sometimes uses province codes; those can be found
at http://www.cdnnet.ca/info/application-form.
The UK also uses
- plc and ltd for businesses
- gov for governmental sites
- mod for Ministry of Defence
- net for networks
- nhs for the National Health Service
- org for non-commercial organizations
- sch for schools
(Note that unlike in the US, "school" in the UK means ONLY pre-university
institutions, what in the US would be called K-12.)
France uses
- asso for associations
- barreau for barristers (lawyers)
- cci for Chambers of Commerce
- cesi for Centers of Secondary Industrial Education (if
I translated it correctly)
- dXXX department numbered XXX (geographic region sort
of like a U.S. county)
- gouv government
- presse press (e.g. newspapers)
- tm trademark
There are a bunch of subdomains that have been defined in the
us domain, including:
- fed.us for federal government
- dni.us for Distributed National Institutes
- nsn.us for Native Sovereign Nations for various Native
American tribal entities
- isa.us or Inter-State Authorities (like port authorities)
- uscourt.gov.us for federal courts
- state.XX.us for state government
- tec.XX.us for technical schools (in state XX)
- ci.YY.XX.us or city.YY.XX.us for city government
(in city YY)
- co.ZZ.XX.us or county.ZZ.XX.us for county government
(in county ZZ)
- cog.XX.us for Council Of Government, for cross-jurisdictional
governing bodies (like water quality or regional transportation
boards)
- district.XX.us or dst for for administrative districts
that cross city or county boundaries (like school, water, or sanitation
districts sometimes do)
- lib.XX.us for libraries
- mus.XX.us for museums
- gen.XX.us for general, non-business state-wide organizations
These rules are not always followed. For example, the State of California
uses ca.gov when it really should use state.ca.us. Also,
some of these categories are extremely rare. I've never seen a dni
or a tec, for example.
Now Wait A Minute!
You may have noticed that some sites that don't seem to match their
extensions. The domain internet.tv is in Canada, not in Tuvalu.
Why does America On-Line use aol.com instead of aol.net?
Why is netsurf.to in the United States?
Basically, money. The countries of Tuvalu and Tonga have raised
badly-needed cash by selling the rights to their extensions to outside
parties, who then sell them to other bidders. (They think that the
English word "to" and the common abbreviation "TV" for "television"
are worth something as extensions.) And since .com is what
people try first when looking for a company, many entities chose
to use that instead of something in their country's two-letter top-level
domain.
There are also some classes of organization that don't fit any
of the domains particularly well. Individuals who want to put up
a web page are not companies, nor non-profits, nor military. For-profit
arts organizations don't fit comfortably in either .com or
.org.
Take all domain names with a grain of salt. There are no penalties
for taking a name in the "wrong" domain, so when people think it
will get them some advantage, it happens.
Go on to Bibliography
Go back to the beginning
Go back to Acronyms and Jargon
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