What we think we know about reionization

Knowing when and how the gas in deep spaced was ionized by early galaxies is critical for studying both galaxy evolution and cosmology. In recent years there have been major strides towards understanding the reionization epoch that have come from a wide range of observables and ever-improving models. I will give an overview of what we think we know about reionization, focusing on insights into the early IGM from quasar absorption lines. Our current picture suggests that reionization ended far later than previously believed, although significant questions remain about the exact timing and the sources that were responsible