We can now see many galaxies as they were within the first billion years after the Big Bang, and we have moved to a model of cosmology in which a mysterious 'dark energy' is the main component of the Universe. Bold new theories and a range of ground- and space-based instruments promise to provide further Insights into the formation and evolution of our Universe. To highlight recent advances, Nature has commissioned a diverse group of people to write about their subjects and how they are developing our understanding of the Universe.
