ISO basic Latin alphabet
Aa	Bb	Cc	Dd
Ee	Ff	Gg	Hh
Ii	Jj	Kk	Ll
Mm	Nn	Oo	Pp
Qq	Rr	Ss	Tt
Uu	Vv	Ww	Xx
Yy	Zz

U (named u /ˈjuː/, plural ues)^[1][2] is the twenty-first letter in the ISO basic Latin alphabet and a vowel in the English alphabet. It is the chemical symbol for uranium.

  History

The letter U ultimately comes from the Semitic letter Waw by way of the letter Y. See the letter Y for details.

During the late Middle Ages, two forms of "v" developed, which were both used for its ancestor u and modern v. The pointed form "v" was written at the beginning of a word, while a rounded form "u" was used in the middle or end, regardless of sound. So whereas valor and excuse appeared as in modern printing, "have" and "upon" were printed haue and vpon. The first distinction between the letters "u" and "v" is recorded in a Gothic alphabet from 1386, where "v" preceded "u". By the mid-16th century, the "v" form was used to represent the consonant and "u" the vowel sound, giving us the modern letter "u". Capital "U" was not accepted as a distinct letter until many years later.^[3]

  Usage

In most languages that use the Latin alphabet, ⟨U⟩ represents the close back rounded vowel /u/. In English it commonly represents /ʌ/ or /ʊ/ ("short U") as in duck, or /ju(ː)/ ("long U") as in mule. Additionally, the letter U is used in text messaging and internet and other written slang to denote you, by virtue of both being pronounced [juː]. In French the letter represents the close front rounded vowel; /u/ is represented by ⟨ou⟩.

  Related letters and other similar characters

• Υ υ : Greek letter Upsilon
• У у : Cyrillic letter U
• V v : Latin letter V
• W w : Latin letter W
• Μ μ : Greek letter Mu
• Ŭ ŭ : Latin letter U with breve
• Ü ü : Latin letter U with diaeresis/umlaut
• Ʉ ʉ : Latin letter U with bar

  Computing codes

¹ and all encodings based on ASCII, including the DOS, Windows, ISO-8859 and Macintosh families of encodings.

  Other representations

NATO phonetic	Morse code
Uniform	··–

Signal flag	Flag semaphore	Braille

  References

  External links

• Media related to U at Wikimedia Commons
• The Wiktionary entry for U
• The Wiktionary entry for u

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (June 2012)

.us

Introduced	1985
TLD type	Country code top-level domain
Status	Active
Registry	Neustar
Sponsor	United States Department of Commerce
Intended use	Entities connected with  United States
Actual use	Was formerly the primary domain name used by state and local governments in the United States, but many of these have since moved to .GOV. Some use by American businesses; relatively popular for domain hacks (e.g. del.icio.us) Most business and commercial use is .com instead.
Registered domains	1,767,085 (June 12 2012)[1]
Registration restrictions	U.S. nexus requirement can be enforced by challenge, but seldom is.
Structure	Originally registrations were within complex, 3rd or 4th level hierarchy, but currently direct second-level registrations are allowed; kids.us permits 3rd-level registrations for child-friendly sites.
Documents	RFC 1480; USDoC agreements with Neustar
Dispute policies	usTLD Dispute Resolution Policy (usDRP)
Website	nic.us
DNSSEC	yes

.us is the Internet country code top-level domain (ccTLD) for the United States and was established in 1985. Registrants of .us domains must be United States citizens, residents, or organizations, or a foreign entity with a presence in the United States. Most registrants in the country have registered for .com, .net, .org and other gTLDs, instead of .us, which has primarily been used by state and local governments despite any entity having the option of registering a .us domain.

  History

The original administrator of .us was Jon Postel of the Information Sciences Institute (ISI) at the University of Southern California (USC). He administered .us under a subcontract that the ISI and USC had from SRI International (which held the .us and the gTLD contract with the United States Department of Defense) and later Network Solutions (which held the .us and the gTLD contract with the National Science Foundation). Registrants could only register third-level domains or higher in a geographic and organizational hierarchy. The vast majority of the geographic subdomains in .us were delegated to various private entities and .us registrants could register with the delegated administrator for the level they wished to register in, but not directly with the .us administrator.

In April 2002, second-level domains under .us became available for registration. The .us domain is currently administered by NeuStar Inc. under a United States Department of Commerce contract.

  Second-level domains for states

Each U.S. state, federal territory, and the District of Columbia has a reserved two-letter second-level domain based on the International Organization for Standardization Standard ISO 3166-2:US for the United States. For example, .ny.us is reserved for websites affiliated with New York and .va.us for those affiliated with Virginia. However, some state administrations prefer usage of .gov domains or others; e.g., California’s chief website is located at www.ca.gov instead of www.state.ca.us, and Massachusetts' chief website is located at www.mass.gov instead of www.state.ma.us.

Additionally, the territories of the US have their own ccTLDs: .as for American Samoa, .gu for Guam, .mp for Northern Mariana Islands, .pr for Puerto Rico, and .vi for the United States Virgin Islands. These operate alongside or in preference to their .us subdomains (i.e., .as.us, .gu.us, .mp.us, .pr.us, and .vi.us, respectively).

  Other administered second-level domains

• .dni.us: distributed national institutes
• .fed.us: federal government agencies (an alternative to .gov)
• .isa.us: interstate agency (only used for the Interstate Mining Compact Commission, imcc.isa.us)
• .kids.us: content "suitable for children under 13"
• .nsn.us: Native sovereign nations (federally recognized Native American tribes)

  Locality-based namespaces

The general format is "<organization-name>.<locality>.<state>.us", where <state> is a state's two-letter postal abbreviation.

Four values of <organization-name> have specific meanings:

• ci: city government agencies (ci.<locality>.<state>.us)
  • Examples: http://ci.boston.ma.us/ or http://ci.sacramento.ca.us/
• town: town government agencies (town.<locality>.<state>.us)
  • Examples: http://town.sandwich.nh.us/ or http://town.windermere.fl.us/
• vil: village government agencies (vil.<locality>.<state>.us)
  • Examples: http://vil.stockbridge.mi.us/ or http://vil.wrightstown.wi.us/
• co: county government agencies (co.<locality>.<state>.us)
  • Examples: http://co.adams.id.us/ or http://co.greene.oh.us/

Ordinarily, a <locality> is a city, county, parish, or township. Some other names may replace the <locality>:

• state: state government agencies (<organization-name>.state.<state>.us)
  • Examples: http://www.state.ak.us/ or http://www.state.mn.us/
• dst: government agencies in administrative districts (<organization-name>.dst.<state>.us)
• cog: councils of government (federations of cities or counties) (<organization-name>.cog.<state>.us)
• k12: public elementary and/or secondary unified school districts (<district-name>.k12.<state>.us), or individual schools (<school-name>.k12.<state>.us)
• pvt.k12: private elementary or secondary schools (<school-name>.pvt.k12.<state>.us)
• cc: community colleges (<school-name>.cc.<state>.us)
• tec: technical and vocational schools (<school-name>.tec.<state>.us)
• lib: public libraries (<library-name>.lib.<state>.us)
• mus: museums (<museum-name>.mus.<state>.us)
• gen: general independent entities (clubs or other groups not fitting into the above categories) (<organization-name>.gen.<state>.us)

In some cases, <locality> and <state> may be combined into a single namespace—for example, many Kentucky school districts have a name of the form area.<kyschools>.us, and even those districts that have a different URL use that form as a redirect to their actual URL. For two examples in the same Kentucky county, Paducah Public Schools are at http://paducah.kyschools.us, while the McCracken County Public Schools use mccracken.kyschools.us as a redirect to their actual URL of http://www.mccrackencountyschools.net.

As noted above, registration of a subdomain in this space may depend on the cooperation of a private delegate. Many mainstream registration companies do not offer domains in this space, which may account for the low utilization rate.

  Restrictions on use of .us domains

Under .US nexus requirements .US domains may be registered only by the following qualified entities:

• Any United States citizen or resident,
• Any United States entity, such as organizations or corporations,
• Any foreign entity or organization with a bona fide presence in the United States

To ensure that these requirements are met, NeuStar frequently conducts "spot checks" on registrant information.

To prevent anonymous registrations that do not meet these requirements, the National Telecommunications and Information Administration has ruled that registrants of .us domains may not secure private domain name registration [1].

Registrants are required to provide complete contact information without omissions. [2]

  See also

• Country code top-level domain

  External links

• .us Domain Registry
• IANA .us whois information
• Management of .us Domain Name (U.S. Department of Commerce)
• usTLD Nexus Requirements - Requirements for registrants of .us domains, Portable Document Format
• Kids.us Content Policies
• RFC 1480: The US Domain (June 1993)
• locality-based namespaces

  References