Toconnectonline，yourcomputermustbeequippedwithamodem，adevicethattranslatesthedigitalsignalsfromyourcomputerintoanalogsignalsthatcantraveloverastandardphoneline.Thosearethescratchysoundsyouhearfromamodem'sspeaker.Believeitornot，thereisactuallymeaninginallthatnoise.Amodemontheotherendofthelinecanunderstanditandconvertsthesoundsbackintodigitalinformation.
Modemscomeindifferentspeedsandaremeasuredinbpsorbitspersecond.A28.8Kbpsmodemsendsdataat28，800bitspersecond.A56Kbpsmodemistwiceasfast，sendingandreceivingdataatarateof56，000bitspersecond.Mostmodemstodayare56Kbps.
Whydoesspeedmatter？OntheInternet，youareconstantlyexchangingdatawithothercomputers.Someofthesedigitalfilescanbequitelarge.Asyouwillsoonlearn，youwantthisexchangetohappenasquicklyaspossible.Ifyouarepurchasingamodem，getthefastestoneavailable.
Modemscomeindifferentspeedsandcanbeinstalledinsideyourcomputer（internal），orconnectedtoyourcomputer'sserialport（external）。Thesedays，almostallcomputerscomeequippedwithaninternalmodem.Butifyouneedtobuyamodemforanoldercomputer，considerpurchasinganexternalonefortworeasons.First，theyaremucheasiertoinstall.Second，occasionallyyourmodemwillfreezeandneedtobereset.Ifyourmodemisexternal，youcansimplyturnitoffandonagain.Ifit'sinternal，theonlywaytoresetitistoturnoffyourcomputerandreboot，whichcantakeseveralminuteseverytimeyouneedtoresetyourmodem.
Toconnectanexternalmodemtoyourcomputer，you'llneedaserialmodemcable.Thecablesareusuallynotincludedwhenyoubuyamodembecausethereareseveraldifferentsizesavailable.Thesecanbepurchasedatanycomputerstorewheremodemsaresold.Mostlikely，yourcomputerwillhaveaconnectoronthebacklabeledserial，orwiththeIOIOIOicon.Thisconnectorcomesinavarietyofformats：9，15，or25pins.Ifyouonlyhaveoneoftheseports，itwillprobablybeCOM1.Ifyouhavetwo，onewillbeCOM1，andtheotherwillbeCOM2.Afteryoupluginyourmodem，youcansignupforInternetService.
UsuallyyoursetupprogramwilltryandfindyourmodemanditsCOMport.Ifitcan't，itwillaskyouwhichCOMportyourmodemisattachedto.Ifyoudon'tknow，theeasiestthingtodoistrythemall.Evenifyouonlyhavetwoserialports，youmaybeabletoselectoneoffourCOMports.Also，therearesomeotherdevicesthatusetheCOMports.Insomecomputers，themouseispluggedintoaserialport.Thisisknownasaserialmouse.Ifyou'vegotaserialmousepluggedintoCOM1，thenjustplugthemodemintoCOM2.Ifyoudon'thaveasecondCOMport，youcanpurchaseacardthatgoesinsideyourcomputerthatwillgiveyouasecondCOMport.Ifthisisnecessary，youshouldcheckwiththemanufacturerofyourcomputer.
Yourmodemwilllikelyhaveaconnectoronthebackwithspacefor25pins.Youneedtomakesurethattheserialmodemcableyoupurchasehastherightnumberofpinsoneitherside，andisthecorrect"gender."Thebestthingtodoistolookatthebackofyourcomputerandlistthevariousconnectors，thenumberofpins，andthegender.Then，whenyougotopurchaseyourmodem，findthecablethatmatchestheconnector.