THE UNIVERSE AT Z-GREATER-THAN-5 - WHEN AND HOW DID THE DARK AGE END

This paper considers how the first subgalactic structures produced the UV radiation that ionized the intergalactic medium before z = 5 and t he ''feedback'' effects of the UV radiation on structure formation. Th e first ''pregalaxies'' may eventually be delectable by their direct U V emission, with characteristic spectral features at Lyman alpha; high -z supernovae may also be detectable. Other probes of the intergalacti c medium beyond z = 5, and of the epochs of reheating and reionization , are discussed, along with possible links between the diffusion of pr egalactic metals and the origin of magnetic fields.