Abstract
Recent optical and ultraviolet (IUE) observations of Herbig-Haro objects are reviewed. The range of emission line ratios occurring in different H-H objects is discussed and compared with the standard shock wave excitation models. The problems with the unusual spectra of some extreme "low excitation" objects are outlined. New continuum measurements are presented and interpreted in terms of the two-photon hypothesis. A number of fundamental parameters derived from spectrophotometric data are discussed. Of special interest are the masses which cover a surprisingly small range of values and the "luminosities" which after including the UV radiation turn out to be surprisingly high.
