Bus Éireann operates intercity routes throughout Ireland, and local services in certain cities other than Dublin. Its headquarters are in Busáras, a shockingly depressing building near the Custom House on the north side of Dublin. It is run on a semi-state basis, which means that the government owns and oversees it, but it is run by its own staff and management, rather than directly by the civil service.
Services are not cheap, considering the lack of comfort on some routes, but the network is fairly extensive, and as Ireland's rail network leaves a great deal to be desired, Bus Éireann may be your only option if you're seeking out "far-flung" places such as Cahirsiveen or Lismore.
Dublin Bus was spun off from Bus Éireann in the 1980s, to operate the capital's commuter bus network.