The expanding Universe was hot and dense during its early evolution. In the first thousand seconds the light nuclides D,(3) He,(4) He and Li-7 were synthesized and, hence, their observed abundances provide a window on the early Universe. The current status of the comparison between the predicted and observed abundances is reviewed and the implications for cosmology and for particle physics are summarized. The ''standard'' hot big bang model is alive and well and is providing valuable information on the evolution of the Universe and, significant contraints on high energy physics.