The discovery and analysis of metal‐poor stars lead to insight into conditions when the Universe and Galaxy were young. We present the rationale for studying such objects (which become progressively rarer at lowest abundance), with a description of their systematic discovery, culminating in the recent analysis of two objects having [Fe/H] < −5.0. We discuss the Metallicity Distribution Function of metal‐poor stars and the abundance patterns of several elements, from Li through to the heavy‐neutron‐capture elements. Relatively few (∼50) stars with [Fe/H] < −3.0 have been analyzed at high spectral resolution and high signal‐to‐noise. As one proceeds to lowest abundance one finds astounding overabundances of some or all of the CNO group and the lighter elements. This diversity among the most metal‐poor stars has yet to be fully understood.