Internet的发展历史 中英文.docx
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Internet的发展历史 中英文.docx
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Internet的发展历史中英文
TheHistoryoftheInternet
TheBeginning-ARPAnet
TheInternetstartedasaprojectbytheUSgovernment.Theobjectoftheprojectwastocreateameansofmunicationsbetweenlongdistancepoints,intheeventofanationwideemergencyor,morespecifically,nuclearwar.TheprojectwascalledARPAnet,anditiswhattheInternetstartedas.Fundedspecificallyformilitarymunication,theengineersresponsibleforARPANethadnoideaofthepossibilitiesofan"Internet."
Bydefinition,an'Internet'isfourormoreputersconnectedbyanetwork.
ARPAnetachieveditsnetworkbyusingaprotocolcalledTCP/IP.Thebasicsaroundthisprotocolwasthatifinformationsentoveranetworkfailedtogetthroughononeroute,itwouldfindanotherroutetoworkwith,aswellasestablishingameansforoneputerto"talk"toanotherputer,regardlessofwhetheritwasaPCoraMacintosh.
Bythe80'sARPAnet,justyearsawayfrombeingthemorewellknownInternet,had200puters.TheDefenseDepartment,satisfiedwithARPAnetsresults,decidedtofullyadoptitintoservice,andconnectedmanymilitaryputersandresourcesintothenetwork.ARPAnetthenhad562putersonitsnetwork.Bytheyear1984,ithadover1000putersonitsnetwork.
In1986ARPAnet(supposedly)shutdown,butonlytheorganizationshut
down,andtheexistingnetworksstillexistedbetweenthemorethan1000
puters.ItshutdownduetoafailiedlinkupwithNSF,whowantedto
connectits5countywidesuperputersintoARPAnet.
WiththefundingofNSF,newhighspeedlinesweresuccessfullyinstalled
atlinespeedsof56k(anormalmodemnowadays)throughtelephonelines
in1988.Bythattime,therewere28,174putersonthe(bythendecided)Internet.In1989therewere80,000putersonit.By1989,therewere290,000.
Anothernetworkwasbuilttosupporttheincrediblenumberofpeople
joining.Itwasconstructedin1992.
Today-TheInternet
Today,theInternethasbeeoneofthemostimportanttechnologicaladvancementsinthehistoryofhumanity.Everyonewantstoget'online'toexperiencethewealthofinformationoftheInternet.MillionsofpeoplenowusetheInternet,andit'spredictedthatbytheyear2003everysinglepersonontheplanetwillhaveInternetaccess.TheInternethastrulybeeawayoflifeinourtimeandera,andisevolvingsoquicklyitshardtodeterminewhereitwillgonext,asputerandnetworktechnologyimproveeveryday.
HOWITWORKS:
It'sastandardthing.PeopleusingtheInternet.Shopping,playinggames,conversinginvirtualInternetenvironments.
TheInternetisnota'thing'itself.TheInternetcannotjust"crash."Itfunctionsthesamewayasthetelephonesystem,onlythereisnoInternetpanythatrunstheInternet.
TheInternetisacollectionofmillioinsofputersthatareallconnectedtoeachother,orhavethemeanstoconnecttoeachother.TheInternetisjustlikeanofficenetwork,onlyithasmillionsofputersconnectedtoit.
ThemainthingabouthowtheInternetworksismunication.HowdoesaputerinHoustonknowhowtoaccessdataonaputerinTokyotoviewawebpage?
Internetmunication,municationamongputersconnectedtotheInternet,isbasedonalanguage.ThislanguageiscalledTCP/IP.TCP/IPestablishesalanguageforaputertoaccessandtransmitdataovertheInternetsystem.
ButTCP/IPassumesthatthereisaphysicalconnecetionbetweenoneputerandanother.Thisisnotusuallythecase.TherewouldhavetobeanetworkwirethatwenttoeveryputerconnectedtotheInternet,butthatwouldmaketheInternetimpossibletoaccess.
Thephysicalconnectionthatisrequireedisestablishedbywayofmodems,phonelines,andothermodemcableconnections(likecablemodemsorDSL).Modemsonputersreadandtransmitdataoverestablishedlines,whichcouldbephonelinesordatalines.Theactualhardcoreconnectionsareestablishedamongputerscalledrouters.
Arouterisaputerthatservesasatrafficcontrollerforinformation.
Toexplainthisbetter,let'slookathowastandardputermightviewawebpage.
1.Theuser'sputerdialsintoanInternetServiceProvider(ISP).TheISPmightinturnbeconnectedtoanotherISP,orastraightconnectionintotheInternetbackbone.
2.TheuserlaunchesawebbrowserlikeNetscapeorInternetExplorerandtypesinaninternetlocationtogoto.
3.Here'swherethetrickypartesin.First,theputersendsdataaboutit'sdatarequesttoarouter.Arouterisaveryhighspeedpowerfulputerrunningspecialsoftware.Thecollectionofroutersintheworldmakewhatiscalleda"backbone,"onwhichallthedataontheInternetistransferred.Thebackbonepresentlyoperatesataspeedofseveralgigabytesper-second.Suchaspeedparedtoanormalmodemislikeparingtheheatofthesuntotheheatofanice-cube.
Routershandledatathatisgoingbackandforth.Arouterputssmallchunksofdataintopackagescalledpackets,whichfunctionsimilarlytoenvelopes.So,whentherequestforthewebpagegoesthrough,itusesTCP/IPprotocolstotelltherouterwhattodowiththedata,whereit'sgoing,andoverallwheretheuserwantstogo.
4.Theroutersendsthesepacketstootherrouters,eventuallyleadingtothetargetputer.It'slikewhisperdownthelane(onlytheinformationremainsintact).
5.Whentheinformationreachesthetargetwebserver,thewebserverthenbeginstosendthewebpageback.Awebserveristheputerwherethewebpageisstoredthatisrunningaprogramthathandlesrequestsforthewebpageandsendsthewebpagetowhoeverwantstoseeit.
6.Thewebpageisputinpackets,sentthroughrouters,andarriveattheusersputerwheretheusercanviewthewebpageonceitisassembled.
Thepacketswhichcontainthedataalsocontainspecialinformationthatletsroutersandotherputersknowhowtoreassemblethedataintherightorder.
Withmillionsofwebpages,andmillionsofusers,usingtheInternetisnotalwayseasyforabeginninguser,especiallyforsomeonewhoisnotentirelyfortalewithusingputers.BelowyoucanfindtipstricksandhelponhowtousemainservicesoftheInternet.
Beforeyouaccesswebpages,youmusthaveawebbrowsertoactuallybeabletoviewthewebpages.MostInternetAccessProvidersprovideyouwithawebbrowserinthesoftwaretheyusuallygivetocustomers;you.Thefactthatyouareviewingthispagemeansthatyouhaveawebbrowser.ThetoptwousebrowsersareNetscapemunicatorandMicrosoftInternetExplorer.Netscapecanbefoundat.netscape.andMSIEcanbefoundat.microsoft./ie.
Thefactthatyou'rereadingthisrightnowmeansthatyouhaveawebbrowser.
Nextyoumustbefamiliarwithactuallyusingwebpages.Awebpageisacollectionofhyperlinks,images,text,forms,menus,andmultimedia.To"navigate"awebpage,simplyclickthelinksitprovidesorfollowit'sowninstructions(likeifithasaformyouneedtouse,itwillprobablyinstructyouhowtouseit).Basically,everythingaboutawebpageismadetobeself-explanetory.Thatisthenatureofawebpage,tobeeasilynavigatable.
"Ohno!
a404error!
'Cannotfindwebpage?
'"isamonremarkmadebynewweb-users.
Sometimeswebsiteshaveerrors.Butanerroronawebsiteisnottheuser'sfault,ofcourse.
A404errormeansthatthepageyoutriedtogotodoesnotexist.Thiscouldbebecausethesiteisstillbeingconstructedandthepagehasn'tbeencreatedyet,orbecausethesiteauthormadeatypointhepage.There'snothingmuchtodoabouta404errorexceptforingthesiteadministrator(ofthepageyouwantedtogoto)antellinghim/herabouttheerror.
AJavascripterroristheresultofaprogrammingerrorintheJavascriptcodeofawebsite.NotallwebsitesutilizeJavascript,butmanydo.JavascriptisdifferentfromJava,andmostbrowsersnowsupportJavascript.Ifyouareusinganoldversionofawebbrowser(Netscape3.0forexample),youmightgetJavascripterrorsbecausesitesutilizeJavascriptversionsthatyourbrowserdoesnotsupport.So,youcantrygettinganewerversionofyourwebbrowser.
standsforElectronicMail,andthat'swhatitis.enablespeopletosendletters,andevenfilesandpicturestoeachother.
Touse,youmusthaveanclient,whichisjustlikeapersonalpostoffice,sinceitretrievesandstores.
Secondly,youmusthaveanaccount.MostInternetServiceProvidersprovidefreeaccount(s)forfree.Someservicesofferfree,likeHotmail,andGeocities.
AfterconfiguringyourclientwithyourPOP3andSMTPserveraddress(yourproviderwillgiveyouthatinformation),youarereadytoreceivemail.
Anattachmentisafilesentinaletter.Ifsomeonesendsyouanattachmentandyoudon'tknowwhoitis,don'trunthefile,ever.Itcouldbeavirusorsomeotherkindofnastyprograms.Youcan'tgetavirusjustbyreading,you'llhavetophysicallyexecutesomeformofprogramforavirustostrike.
Asignatureisafeatureofmanyprograms.Asignatureisaddedtotheendofeveryyousendout.Youcanputatextgraphic,yourbusinessinformation,anythingyouwant.
ImaginethataputerontheInternetisanislandinthesea.Theseaisfilledwithmillionsofislands.ThisistheInternet.Imagineanislandmunicateswithotherislandbysendingshipstootherislandsandreceivingships.Theislandhasportstoacceptandsendoutships.
AputerontheInternethasaccessnodescalledports.Aportisjustasymbolicobjectthatallowstheputertooperateonanetwork(ortheInternet).Thismethodissimilartotheisland/oceansymbolismabove.
Telnetreferstoaccessingportsonaserverdirectlywithatextconnection.AlmosteverykindofInternetfunction,likeaccessingwebpages,"chatting,"andingisdoneoveraTelnetconnection.
TelnettingrequiresaTelnetclient.Atelnetprogrameswit
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