All domestic dogs bark – wild dogs, as a rule do not.
Why domesticated dogs should do so is open to speculation, but one suggestion is that they are trying to imitate human speech.
How we transcribe the sounds dogs make varies from country to country. In the UK the bark is often written as “bow-wow” or “woof-woof.” The Spanish hear “guau-guau”; Swedish dogs go “Voff-voff” and in Finland dogs say “Hau-Hau.” And if Tintin’s Snowy is typical then Belgian dogs go “wooah-wooah.”
One thing all nations seem to be agreed on is that dogs never emit a single bark.