The nature of dark matter is one of the most captivating and fundamental open problems facing physicists today. Over many decades, we have collected overwhelming evidence for the existence of dark matter in the universe.  Some of the strongest evidence comes from observations of the growth of galaxies and clusters of galaxies, from tiny clumps of matter at the earliest times to the vast patterns of stellar structures that we see in our telescopes today. These patterns are created by streams of dark matter coming together under the influence of their gravitational attraction. There are new ideas about dark matter in which these streams are not completely dark but, rather, can be coaxed into revealing themselves as they shine ever so faintly. This talk will review our knowledge of dark matter, and describe new methods for revealing its flow being developed here at SLAC.