MostWebsitesneedtoselectivelyrestrictaccesstosomeportionsofthesite.YoucanthinkofaWebsiteassomewhatanalogoustoanartgallery.Thegalleryisopenforthepublictocomeinandbrowse,buttherearecertainpartsofthefacility,suchasthebusinessoffices,thatareaccessibleonlytopeoplewithcertaincredentials,suchasemployees.WhenaWebsitestoresitscustomers'creditcardinformationinadatabase,forexample,accesstothedatabasem...