Internet

VisualizationofthevariousroutesthroughaportionoftheInternet.

TheInternetisaworldwide,publiclyaccessibleseriesofinterconnectedcomputernetworksthattransmitdatabypacketswitchingusingthestandardInternetProtocol(IP).Itisa"networkofnetworks"thatconsistsofmillionsofsmallerdomestic,academic,business,andgovernmentnetworks,whichtogethercarryvariousinformationandservices,suchaselectronicmail,onlinechat,filetransfer,andtheinterlinkedWebpagesandotherdocumentsoftheWorldWideWeb.

Terminology:Internetvs.WorldWideWeb

TheInternetandtheWorldWideWebarenotsynonymous.TheInternetisacollectionofinterconnectedcomputernetworks,linkedbycopperwires,fiber-opticcables,wirelessconnections,etc.Incontrast,theWebisacollectionofinterconnecteddocumentsandotherresources,linkedbyhyperlinksandURLs.TheWorldWideWebisoneoftheservicesaccessibleviatheInternet,alongwithmanyothersincludinge-mail,filesharingandothersdescribedbelow.

TheInternetprotocolsuiteisacollectionofstandardsandprotocolsorganizedintolayerssothateachlayerprovidesthefoundationandtheservicesrequiredbythelayerabove.Inthisscheme,theInternetconsistsofthecomputersandnetworksthathandleInternetProtocol(IP)datapackets.TransmissionControlProtocol(TCP)dependsonIPandsolvesproblemslikedatapacketsarrivingoutoforderornotatall.NextcomesHypertextTransferProtocol(HTTP),whichisanapplicationlayerprotocol.ItrunsontopofTCP/IPandprovidesuseragents,suchaswebbrowsers,withaccesstothefiles,documentsandotherresourcesoftheWorldWideWeb.

History

Creation

TheUSSR'slaunchofSputnikspurredtheUnitedStatestocreatetheAdvancedResearchProjectsAgency,knownasARPA,inFebruary1958toregainatechnologicallead.ARPAcreatedtheInformationProcessingTechnologyOffice(IPTO)tofurthertheresearchoftheSemiAutomaticGroundEnvironment(SAGE)program,whichhadnetworkedcountry-wideradarsystemstogetherforthefirsttime.J.C.R.LickliderwasselectedtoheadtheIPTO,andsawuniversalnetworkingasapotentialunifyinghumanrevolution.

LicklidermovedfromthePsycho-AcousticLaboratoryatHarvardUniversitytoMITin1950,afterbecominginterestedininformationtechnology.AtMIT,heservedonacommitteethatestablishedLincolnLaboratoryandworkedontheSAGEproject.In1957hebecameaVicePresidentatBBN,whereheboughtthefirstproductionPDP-1computerandconductedthefirstpublicdemonstrationoftime-sharing.

AttheIPTO,LickliderrecruitedLawrenceRobertstoheadaprojecttoimplementanetwork,andRobertsbasedthetechnologyontheworkofPaulBaranwhohadwrittenanexhaustivestudyforthe.AirForcethatrecommendedpacketswitching(asopposedtocircuitswitching)tomakeanetworkhighlyrobustandsurvivable.Aftermuchwork,thefirsttwonodesofwhatwouldbecometheARPANETwereinterconnectedbetweenUCLAandSRIInternationalinMenloPark,California,onOctober291969.TheARPANETwasoneofthe"eve"networksoftoday'sInternet.FollowingonfromthedemonstrationthatpacketswitchingworkedontheARPANET,theBritishPostOffice,Telenet,DATAPACandTRANSPACcollaboratedtocreatethefirstinternationalpacketswitchednetworkservice.IntheUK,thiswasreferredtoastheInternationalPacketStreamService(IPSS),in1978.ThecollectionofnetworksgrewfromEuropeandtheUStocoverCanada,HongKongandAustraliaby1981.ThepacketswitchingstandardwasdevelopedintheCCITT(nowcalledITU-T)around1976.wasindependentoftheTCP/IPprotocolsthatarosefromtheexperimentalworkofDARPAontheARPANET,PacketRadioNetandPacketSatelliteNetduringthesametimeperiod.VintonCerfandRobertKahndevelopedthefirstdescriptionoftheTCPprotocolsduring1973andpublishedapaperonthesubjectinMay1974.Useoftheterm"Internet"todescribeasingleglobalTCP/IPnetworkoriginatedinDecember1974withthepublicationofRFC674,thefirstfullspecificationofTCPthatwaswrittenbyVintonCerf,YogenDalalandCarlSunshinethenatStanfordUniversity.Duringthenextnineyears,workproceededtorefinetheprotocolsandtoimplementthemonawiderangeofoperatingsystems.

ThefirstTCP/IP-wideareanetworkwasmadeoperationalbyJanuary11983whenallhostsontheARPANETwereswitchedoverfromtheolderNCPprotocolstoTCP/IP.In1985,theUnitedStates'NationalScienceFoundation(NSF)commissionedtheconstructionofauniversity56kilobit/secondnetworkbackboneusingcomputerscalled"fuzzballs"bytheirinventor,DavidMills.Thefollowingyear,NSFsponsoredthedevelopmentofahigherspeedmegabit/secondbackbonethatbecometheNSFNet.AkeydecisiontousetheDARPATCP/IPprotocolswasmadebyDennisJennings,theninchargeoftheSupercomputerprogramatNSF.

Theopeningofthenetworktocommercialinterestsbeganin1988.TheUSFederalNetworkingCouncilapprovedtheinterconnectionoftheNSFNETtothecommercialMCIMailsysteminthatyearandthelinkwasmadeinthesummerof1989.Othercommercialelectronicemailservicesweresoonconnected,includingOnTyme,TelemailandCompuserve.Inthatsameyear,threecommercialInternetServiceProviderswerecreated:UUNET,PSINETandCERFNET.Important,separatenetworksthatofferedgatewaysinto,thenlatermergedwiththeInternetincludeUsenetandBITNET.Variousothercommercialandeducationalnetworks,suchasTelenet,Tymnet,CompuserveandJANETwereinterconnectedwiththegrowingInternet.Telenet(latercalledSprintnet)wasalargeprivately-fundednationalcomputernetworkwithfreedial-upaccessincitiesthroughoutthe.thathadbeeninoperationsincethe1970s.Thisnetworkwaseventuallyinterconnectedwiththeothersinthe1980sastheTCP/IPprotocolbecameincreasinglypopular.TheabilityofTCP/IPtoworkovervirtuallyanypre-existingcommunicationnetworksallowedforagreateaseofgrowthalthoughtherapidgrowthoftheInternetwasdueprimarilytotheavailabilityofcommercialroutersfromcompaniessuchasCiscoSystems,ProteonandJuniper,theavailabilityofcommercialEthernetequipmentforlocalareanetworkingandthewidespreadimplementationofTCP/IPontheUNIXoperatingsystem.

Growth

Thenetworkgainedapublicfaceinthe1990s.OnAugust61991,CERN,whichstraddlestheborderbetweenFranceandSwitzerland,publicizedthenewWorldWideWebproject,twoyearsafterBritishscientistTimBerners-LeehadbeguncreatingHTML,HTTPandthefirstfewWebpagesatCERN.

AnearlypopularwebbrowserwasViolaWWWbaseduponHyperCard.ItwaseventuallyreplacedinpopularitybytheMosaicwebbrowser.In1993theNationalCenterforSupercomputingApplicationsattheUniversityofIllinoisreleasedversionofMosaic,andbylate1994therewasgrowingpublicinterestinthepreviouslyacademic/technicalInternet.By1996usageoftheword"Internet"hadbecomecommonplace,andconsequently,sohaditsmisusageasareferencetotheWorldWideWeb.

Meanwhile,overthecourseofthedecade,theInternetsuccessfullyaccommodatedthemajorityofpreviouslyexistingpubliccomputernetworks(althoughsomenetworks,suchasFidoNet,haveremainedseparate)Duringthe1990s,itwasestimatedthattheInternetgrewby100%peryear,withabriefperiodofexplosivegrowthin1996and1997.Thisgrowthisoftenattributedtothelackofcentraladministration,whichallowsorganicgrowthofthenetwork,aswellasthenon-proprietaryopennatureoftheInternetprotocols,whichencouragesvendorinteroperabilityandpreventsanyonecompanyfromexertingtoomuchcontroloverthenetwork.

Today'sInternet

Arackofservers

Asidefromthecomplexphysicalconnectionsthatmakeupitsinfrastructure,theInternetisfacilitatedbybi-ormulti-lateralcommercialcontracts.,peeringagreements),andbytechnicalspecificationsorprotocolsthatdescribehowtoexchangedataoverthenetwork.Indeed,theInternetisessentiallydefinedbyitsinterconnectionsandroutingpolicies.

AsofSeptember302007,billionpeopleusetheInternetaccordingtoInternetWorldStats.WritingintheHarvardInternationalReview,philosopherawriteronpolicyissuesfortheWashingtonDC-basedUrbanLandInstitute,hasassertedthattheInternetisfastbecomingabasicfeatureofglobalcivilization,sothatwhathastraditionallybeencalled"civilsociety"isnowbecomingidenticalwithinformationtechnologysocietyasdefinedbyInternetuse.

Internetprotocols

Inthiscontext,therearethreelayersofprotocols:

Atthelowerlevel(OSIlayer3)isIP(InternetProtocol),whichdefinesthedatagramsorpacketsthatcarryblocksofdatafromonenodetoanother.Thevastmajorityoftoday'sInternetusesversionfouroftheIPprotocol.IPv4),andalthoughIPv6isstandardized,itexistsonlyas"islands"ofconnectivity,andtherearemanyISPswithoutanyIPv6connectivity..ICMP(InternetControlMessageProtocol)alsoexistsatthislevel.ICMPisconnectionless;itisusedforcontrol,signaling,anderrorreportingpurposes.

TCP(TransmissionControlProtocol)andUDP(UserDatagramProtocol)existatthenextlayerup(OSIlayer4);thesearetheprotocolsbywhichdataistransmitted.TCPmakesavirtual'connection',whichgivessomelevelofguaranteeofreliability.UDPisabest-effort,connectionlesstransport,inwhichdatapacketsthatarelostintransitwillnotbere-sent.

TheapplicationprotocolssitontopofTCPandUDPandoccupylayers5,6,and7oftheOSImodel.Thesedefinethespecificmessagesanddataformatssentandunderstoodbytheapplicationsrunningateachendofthecommunication.ExamplesoftheseprotocolsareHTTP,FTP,andSMTP.

Internetstructure

TherehavebeenmanyanalysesoftheInternetanditsstructure.Forexample,ithasbeendeterminedthattheInternetIProutingstructureandhypertextlinksoftheWorldWideWebareexamplesofscale-freenetworks.

SimilartothewaythecommercialInternetprovidersconnectviaInternetexchangepoints,researchnetworkstendtointerconnectintolargesubnetworkssuchas:

GEANT

GLORIAD

TheInternet2Network(formallyknownastheAbileneNetwork)

JANET(theUK'snationalresearchandeducationnetwork)

Theseinturnarebuiltaroundrelativelysmallernetworks.Seealsothelistofacademiccomputernetworkorganizations

Innetworkdiagrams,theInternetisoftenrepresentedbyacloudsymbol,intoandoutofwhichnetworkcommunicationscanpass.

ICANN

ICANNheadquartersinMarinaDelRey

TheInternetCorporationforAssignedNamesandNumbers(ICANN)istheauthoritythatcoordinatestheassignmentofuniqueidentifiersontheInternet,includingdomainnames,InternetProtocol(IP)addresses,andprotocolportandparameternumbers.Agloballyunifiednamespace.,asystemofnamesinwhichthereisoneandonlyoneholderofeachname)isessentialfortheInternettofunction.ICANNisheadquarteredinMarinadelRey,California,butisoverseenbyaninternationalboardofdirectorsdrawnfromacrosstheInternettechnical,business,academic,andnon-commercialcommunities.TheUSgovernmentcontinuestohavetheprimaryroleinapprovingchangestotherootzonefilethatliesattheheartofthedomainnamesystem.BecausetheInternetisadistributednetworkcomprisingmanyvoluntarilyinterconnectednetworks,theInternet,assuch,hasnogoverningbody.ICANN'sroleincoordinatingtheassignmentofuniqueidentifiersdistinguishesitasperhapstheonlycentralcoordinatingbodyontheglobalInternet,butthescopeofitsauthorityextendsonlytotheInternet'ssystemsofdomainnames,IPaddresses,andprotocolportandparameternumbers.

OnNovember162005,theWorldSummitontheInformationSociety,heldinTunis,establishedtheInternetGovernanceForum(IGF)todiscussInternet-relatedissues.

Language

TheprevalentlanguageforcommunicationontheInternetisEnglish.ThismaybearesultoftheInternet'sorigins,aswellasEnglish'sroleasthelinguafranca.Itmayalsoberelatedtothepoorcapabilityofearlycomputers,largelyoriginatingintheUnitedStates,tohandlecharactersotherthanthoseintheEnglishvariantoftheLatinalphabet.

AfterEnglish(30%ofWebvisitors)themost-requestedlanguagesontheWorldWideWebareChinese14%,Spanish8%,Japanese8%,German5%,French5%,Portuguese%,Korean3%,Italian3%andArabic%(fromInternetWorldStats,updatedJanuary11,2007).

Bycontinent,36%oftheworld'sInternetusersarebasedinAsia,29%inEurope,and21%inNorthAmerica.

TheInternet'stechnologieshavedevelopedenoughinrecentyears,especiallyintheuseofUnicode,thatgoodfacilitiesareavailablefordevelopmentandcommunicationinmostwidelyusedlanguages.However,someglitchessuchasmojibake(incorrectdisplayofforeignlanguagecharacters,alsoknownaskryakozyabry)stillremain.

Internetandtheworkplace

TheInternetisallowinggreaterflexibilityinworkinghoursandlocation,especiallywiththespreadofunmeteredhigh-speedconnectionsandWebapplications.

TheInternetViewedonMobileDevices

TheInternetcannowbeaccessedvirtuallyanywherebynumerousmeans.Mobilephones,datacards,handheldgameconsolesandcellularroutersallowuserstoconnecttotheInternetfromanywherethereisacellularnetworksupportingthatdevice'stechnology.

CommonusesoftheInternet

E-mail

TheconceptofsendingelectronictextmessagesbetweenpartiesinawayanalogoustomailinglettersormemospredatesthecreationoftheInternet.EventodayitcanbeimportanttodistinguishbetweenInternetandinternale-mailsystems.Internete-mailmaytravelandbestoredunencryptedonmanyothernetworksandmachinesoutofboththesender'sandtherecipient'scontrol.Duringthistimeitisquitepossibleforthecontenttobereadandeventamperedwithbythirdparties,ifanyoneconsidersitimportantenough.Purelyinternalorintranetmailsystems,wheretheinformationneverleavesthecorporateororganization'snetwork,aremuchmoresecure,althoughinanyorganizationtherewillbeITandotherpersonnelwhosejobmayinvolvemonitoring,andoccasionallyaccessing,theemailofotheremployeesnotaddressedtothem.

TheWorldWideWeb

Graphicrepresentationoflessthan%oftheWWW,representingsomeofthehyperlinks

ManypeopleusethetermsInternetandWorldWideWeb(orjusttheWeb)interchangeably,but,asdiscussedabove,thetwotermsarenotsynonymous.

TheWorldWideWebisahugesetofinterlinkeddocuments,imagesandotherresources,linkedbyhyperlinksandURLs.ThesehyperlinksandURLsallowtheweb-serversandothermachinesthatstoreoriginals,andcachedcopies,oftheseresourcestodeliverthemasrequiredusingHTTP.HTTPisonlyoneofthecommunicationprotocolsusedontheInternet.

WebservicesalsouseHTTPtoallowsoftwaresystemstocommunicateinordertoshareandexchangebusinesslogicanddata.

SoftwareproductsthatcanaccesstheresourcesoftheWebarecorrectlytermeduseragents.Innormaluse,Webbrowsers,suchasInternetExplorerandFirefoxaccessWebpagesandallowuserstonavigatefromonetoanotherviahyperlinks.Webdocumentsmaycontainalmostanycombinationofcomputerdataincludingphotographs,graphics,sounds,text,video,multimediaandinteractivecontentincludinggames,officeapplicationsandscientificdemonstrations.

Throughkeyword-drivenInternetresearchusingsearchengines,likeYahoo!,andGoogle,millionsofpeopleworldwidehaveeasy,instantaccesstoavastanddiverseamountofonlineinformation.Comparedtoencyclopediasandtraditionallibraries,theWorldWideWebhasenabledasuddenandextremedecentralizationofinformationanddata.

ItisalsoeasierusingtheWebthaneverbeforeforindividualsandorganisationstopublishideasandinformationtoanextremelylargeaudience.Anyonecanfindwaystopublishawebpageorbuildawebsiteforverylittleinitialcost.Publishingandmaintaininglarge,professionalwebsitesfullofattractive,diverseandup-to-dateinformationisstilladifficultandexpensiveproposition,however.

Manyindividualsandsomecompaniesandgroupsuse"Weblogs"orblogs,whicharelargelyusedaseasily-updatableonlinediaries.Somecommercialorganizationsencouragestafftofillthemwithadviceontheirareasofspecializationinthehopethatvisitorswillbeimpressedbytheexpertknowledgeandfreeinformation,andbeattractedtothecorporationasaresult.OneexampleofthispracticeisMicrosoft,whoseproductdeveloperspublishtheirpersonalblogsinordertopiquethepublic'sinterestintheirwork.

CollectionsofpersonalWebpagespublishedbylargeserviceprovidersremainpopular,andhavebecomeincreasinglysophisticated.WhereasoperationssuchasAngelfireandGeoCitieshaveexistedsincetheearlydaysoftheWeb,newerofferingsfrom,forexample,FacebookandMySpacecurrentlyhavelargefollowings.TheseoperationsoftenbrandthemselvesassocialnetworkservicesratherthansimplyasWebpagehosts.

AdvertisingonpopularWebpagescanbelucrative,ande-commerceorthesaleofproductsandservicesdirectlyviatheWebcontinuestogrow.

Intheearlydays,WebpageswereusuallycreatedassetsofcompleteandisolatedHTMLtextfilesstoredonaWebserver.Morerecently,Websitesaremoreoftencreatedusingcontentmanagementsystem(CMS)softwarewith,initially,verylittlecontent.UsersoftheCMS,whomaybepaidstaff,membersofacluborotherorganisation,orevenmembersofthepublic,filltheCMSdatabasewithcontentusingeditingpagesdesignedforthatpurpose,whilecasualvisitorsviewandreadthiscontentinitsfinalHTMLform.Theremayormaynotbeeditorial,approvalandsecuritysystemsbuiltintotheprocessoftakingnewlyenteredcontentandmakingitavailabletothetargetvisitors.

Remoteaccess

TheInternetallowscomputeruserstoconnecttoothercomputersandinformationstoreseasily,wherevertheymaybeacrosstheworld.Theymaydothiswithorwithouttheuseofsecurity,authenticationandencryptiontechnologies,dependingontherequirements.

Thisisencouragingnewwaysofworkingfromhome,collaborationandinformationsharinginmanyindustries.Anaccountantsittingathomecanauditthebooksofacompanybasedinanothercountry,onaserversituatedinathirdcountrythatisremotelymaintainedbyITspecialistsinafourth.Theseaccountscouldhavebeencreatedbyhome-workingbook-keepers,inotherremotelocations,basedoninformatione-mailedtothemfromofficesallovertheworld.SomeofthesethingswerepossiblebeforethewidespreaduseoftheInternet,butthecostofprivate,leasedlineswouldhavemademanyoftheminfeasibleinpractice.

Anofficeworkerawayfromhisdesk,perhapstheothersideoftheworldonabusinesstriporaholiday,canopenaremotedesktopsessionintotheirnormalofficePCusingasecureVirtualPrivateNetwork(VPN)connectionviatheInternet.Thisgivestheworkercompleteaccesstoalloftheirnormalfilesanddata,includinge-mailandotherapplications,whileawayfromtheoffice.

ThisconceptisalsoreferredtobysomenetworksecuritypeopleastheVirtualPrivateNightmare,becauseitextendsthesecureperimeterofacorporatenetworkintoitsemployees'homes;thishasbeenthesourceofsomenotablesecuritybreaches,butalsoprovidessecurityfortheworkers.

Collaboration

Thelowcostandnearlyinstantaneoussharingofideas,knowledge,andskillshasmadecollaborativeworkdramaticallyeasier.Notonlycanagroupcheaplycommunicateandtest,butthewidereachoftheInternetallowssuchgroupstoeasilyforminthefirstplace,evenamongnicheinterests.AnexampleofthisisthefreesoftwaremovementinsoftwaredevelopmentwhichproducedGNUandLinuxfromscratchandhastakenoverdevelopmentofMozillaand(formerlyknownasNetscapeCommunicatorandStarOffice).

Internet'chat',whetherintheformofIRC'chatrooms'orchannels,orviainstantmessagingsystemsallowcolleaguestostayintouchinaveryconvenientwaywhenworkingattheircomputersduringtheday.Messagescanbesentandviewedevenmorequicklyandconvenientlythanviae-mail.Extensiontothesesystemsmayallowfilestobeexchanged,'whiteboard'drawingstobesharedaswellasvoiceandvideocontactbetweenteammembers.

Versioncontrolsystemsallowcollaboratingteamstoworkonsharedsetsofdocumentswithouteitheraccidentallyoverwritingeachother'sworkorhavingmemberswaituntiltheyget'sent'documentstobeabletoaddtheirthoughtsandchanges.

Filesharing

Acomputerfilecanbee-mailedtocustomers,colleaguesandfriendsasanattachment.ItcanbeuploadedtoaWebsiteorFTPserverforeasydownloadbyothers.Itcanbeputintoa"sharedlocation"orontoafileserverforinstantusebycolleagues.Theloadofbulkdownloadstomanyuserscanbeeasedbytheuseof"mirror"serversorpeer-to-peernetworks.

Inanyofthesecases,accesstothefilemaybecontrolledbyuserauthentication;thetransitofthefileovertheInternetmaybeobscuredbyencryptionandmoneymaychangehandsbeforeorafteraccesstothefileisgiven.Thepricecanbepaidbytheremotechargingoffundsfrom,forexampleacreditcardwhosedetailsarealsopassed—hopefullyfullyencrypted—acrosstheInternet.TheoriginandauthenticityofthefilereceivedmaybecheckedbydigitalsignaturesorbyMD5orothermessagedigests.

ThesesimplefeaturesoftheInternet,overaworld-widebasis,arechangingthebasisfortheproduction,sale,anddistributionofanythingthatcanbereducedtoacomputerfilefortransmission.Thisincludesallmannerofprintpublications,softwareproducts,news,music,film,video,photography,graphicsandtheotherarts.Thisinturnhascausedseismicshiftsineachoftheexistingindustriesthatpreviouslycontrolledtheproductionanddistributionoftheseproductsinthatcountry.

Internetcollaborationtechnologyenablesbusinessandprojectteamstosharedocuments,calendarsandotherinformation.Suchcollaborationoccursinawidevarietyofareasincludingscientificresearch,softwaredevelopment,conferenceplanning,politicalactivismandcreativewriting.

Streamingmedia

ManyexistingradioandtelevisionbroadcastersprovideInternet'feeds'oftheirliveaudioandvideostreams(forexample,theBBCandRushLimbaugh).Theymayalsoallowtime-shiftviewingorlisteningsuchasPreview,ClassicClipsandListenAgainfeatures.TheseprovidershavebeenjoinedbyarangeofpureInternet'broadcasters'whoneverhadon-airlicenses.ThismeansthatanInternet-connecteddevice,suchasacomputerorsomethingmorespecific,canbeusedtoaccesson-linemediainmuchthesamewayaswaspreviouslypossibleonlywithatelevisionorradioreceiver.Therangeofmaterialismuchwider,frompornographytohighlyspecializedtechnicalWeb-casts.Podcastingisavariationonthistheme,where—usuallyaudio—materialisfirstdownloadedinfullandthenmaybeplayedbackonacomputerorshiftedtoadigitalaudioplayertobelistenedtoonthemove.Thesetechniquesusingsimpleequipmentallowanybody,withlittlecensorshiporlicensingcontrol,tobroadcastaudio-visualmaterialonaworldwidebasis.

Webcamscanbeseenasanevenlower-budgetextensionofthisphenomenon.Whilesomewebcamscangivefullframeratevideo,thepictureisusuallyeithersmallorupdatesslowly.InternetuserscanwatchanimalsaroundanAfricanwaterhole,shipsinthePanamaCanal,thetrafficatalocalroundaboutortheirownpremises,liveandinrealtime.Videochatrooms,videoconferencing,andremotecontrollablewebcamsarealsopopular.Manyusescanbefoundforpersonalwebcamsinandaroundthehome,withandwithouttwo-waysound.

Voicetelephony(VoIP)

VoIPstandsforVoiceoverIP,whereIPreferstotheInternetProtocolthatunderliesallInternetcommunication.Thisphenomenonbeganasanoptionaltwo-wayvoiceextensiontosomeoftheInstantMessagingsystemsthattookoffaroundtheyear2000.InrecentyearsmanyVoIPsystemshavebecomeaseasytouseandasconvenientasanormaltelephone.Thebenefitisthat,astheInternetcarriestheactualvoicetraffic,VoIPcanbefreeorcostmuchlessthananormaltelephonecall,especiallyoverlongdistancesandespeciallyforthosewithalways-onInternetconnectionssuchascableorADSL.

ThusVoIPismaturingintoaviablealternativetotraditionaltelephones.Interoperabilitybetweendifferentprovidershasimprovedandtheabilitytocallorreceiveacallfromatraditionaltelephoneisavailable.SimpleinexpensiveVoIPmodemsarenowavailablethateliminatetheneedforaPC.

Voicequalitycanstillvaryfromcalltocallbutisoftenequaltoandcanevenexceedthatoftraditionalcalls.

RemainingproblemsforVoIPincludeemergencytelephonenumberdiallingandreliability.CurrentlyafewVoIPprovidersprovideanemergencyservicebutitisnotuniversallyavailable.Traditionalphonesarelinepoweredandoperateduringapowerfailure,VoIPdoesnotdosowithoutabackuppowersourcefortheelectronics.

MostVoIPprovidersofferunlimitednationalcallingbutthedirectioninVoIPisclearlytowardglobalcoveragewithunlimitedminutesforalowmonthlyfee.

VoIPhasalsobecomeincreasinglypopularwithinthegamingworld,asaformofcommunicationbetweenplayers.PopulargamingVoIPclientsincludeVentriloandTeamspeak,andthereareothersavailablealso.

Censorship

Somegovernments,suchasthoseofCuba,Iran,NorthKorea,thePeople'sRepublicofChinaandSaudiArabia,restrictwhatpeopleintheircountriescanaccessontheInternet,especiallypoliticalandreligiouscontent.Thisisaccomplishedthroughsoftwarethatfiltersdomainsandcontentsothattheymaynotbeeasilyaccessedorobtainedwithoutelaboratecircumvention.

InNorway,FinlandandSweden,majorInternetserviceprovidershavevoluntarily(possiblytoavoidsuchanarrangementbeingturnedintolaw)agreedtorestrictaccesstositeslistedbypolice.WhilethislistofforbiddenURLsisonlysupposedtocontainaddressesofknownchildpornographysites,thecontentofthelistissecret.

Manycountrieshaveenactedlawsmakingtheposse