The primary purpose of this report is to survey the available information mainly experimental, on the subject. Most attention is given to the complex flow field resulting when a 3-D protuberance is introduced into a laminar boundary layer; less can be said about the turbulent case or 2-D protuberances because enough detailed, careful experiments have not been made. There are some features of the induced flow fields common to all speed ranges; applications range from flow in the atmospheric boundary layer to hypersonic vehicle problems. Some attempts to analyze the downstream flow are also summarized.