Primordial Big Bang Nucleosynthesis

Big Bang Nucleosynthesis is the theory of the production of the light element isotopes of D, 3He, 4He, and 7Li. After a brief review of the essential elements of the standard Big Bang model at a temperature of about 1 MeV, the theoretical input and predictions of BBN are discussed. The theory is tested by the observational determinations of the light element abundances and the current status of these observations is reviewed. Concordance of standard model and the related observations is found over a limited range of the baryon-to-photon ratio, the single true parameter of the standard model. Implications of BBN on chemical evolution, dark matter and constraints on particle properties will be also discussed.