FacebookisasocialnetworkingwebsitethatisoperatedandprivatelyownedbyFacebook,Inc.SinceSeptember2006,anyonewhoconfirmsthemselvestobeovertheageof13withavalide-mailaddresscanbecomeaFacebookuser.Facebook'stargetaudienceismoreforyouthsthanadults.Userscanaddfriendsandsendthemmessages,andupdatetheirpersonalprofilestonotifyfriendsaboutthemselves.Additionally,userscanjoinnetworksorganizedbyworkplace,school,orcollege.Thewebsite'snamestemsfromthecolloquialnameofbooksgiventostudentsatthestartoftheacademicyearbyuniversityadministrationsintheUSwiththeintentionofhelpingstudentstogettoknoweachotherbetter.

　　FacebookwasfoundedbyMarkZuckerbergwithhiscollegeroommatesandfellowcomputersciencestudentsEduardoSaverin,DustinMoskovitzandChrisHughes.Thewebsite'smembershipwasinitiallylimitedbythefounderstoHarvardstudents,butwasexpandedtoothercollegesintheBostonarea,theIvyLeague,andStanfordUniversity.Itlaterexpandedfurthertoinclude(potentially)anyuniversitystudent,thenhighschoolstudents,and,finally,toanyoneaged13andover.Thewebsitecurrentlyhasmorethan400millionactiveusersworldwide.

　　TheoriginalconceptforFacebookwasborrowedfromaproductproducedbyZuckerberg'sprepschoolPhillipsExeterAcademywhichfordecadespublishedanddistributedaprintedmanualofallstudentsandfaculty,unofficiallycalledthe"facebook".

　　Facebookhasmetwithsomecontroversy.IthasbeenblockedintermittentlyinseveralcountriesincludingSyria,China,Vietnam,andIran.Ithasalsobeenbannedatmanyplacesofworktodiscourageemployeesfromwastingtimeusingtheservice.

　　Privacyhasalsobeenanissue,andithasbeencompromisedseveraltimes.Facebooksettledalawsuitregardingclaimsoversourcecodeandintellectualproperty.Thesitehasalsobeeninvolvedincontroversyoverthesaleoffansandfriends.

　　AJanuary2009Compete.comstudyrankedFacebookasthemostusedsocialnetworkbyworldwidemonthlyactiveusers,followedbyMySpace.EntertainmentWeeklyputitonitsend-of-the-decade'best-of'list,saying,"Howonearthdidwestalkourexes,rememberourco-workers'birthdays,bugourfriends,andplayarousinggameofScrabulousbeforeFacebook?"

　　TherehaverecentlybeenreportsofFacebookproposinganinitialpublicoffering(IPO),i.e.issueequitysharesasstocktoinvestors.However,Zuckerbergstressesthatitwillnotbeforafewmoreyears,andthecompanyisinnoneedofadditionalcapital.Also,someanalystsfeartheFacebookIPOmightbeaparticularlyweakone.