Annual review of astronomy and astrophysics vol:36 pages:233-266
We review the wide range of observed properties of Herbig Ae/Be stars and try to combine this rich data set into a consistent picture of their circumstellar environment and evolutionary status. We discuss in some detail the geometry of the circumstellar environment. The presence of disks in Herbig Ae/Be stars is inferred from direct and indirect observational evidence. Envelopes can dominate the spectral energy distributions on large angular scales. In some stars, a fairly massive disk persists until the star has reached the main sequence. The evidence for an evolutionary link between isolated Herbig Ae/Be stars and beta Pictoris is summarized.