Brane-world cosmological perturbations
Brane-world models provide a phenomenology that allows us to explore the cosmological consequences of some M theory ideas, and at the same time to use precision cosmology as a test of these ideas. In order to achieve this, we need to understand how brane-world gravity affects cosmological dynamics and perturbations. This introductory review describes the key features of cosmological perturbations in a brane-world universe.