The first stars, the first manufacturers of metals, are considered to be massive, short-lived, and chemically enriched the surrounding pristine metal-free gas clouds soon after their formation not long after the Big Bang. Their descendants, born out of these chemically enriched gas with the first-star nucleosynthetic elements, are the most metal-poor and are still alive today in the Milky Way and its satellite galaxies. They have preserved the nucleosynthetic signatures of the first stars, their birth environment, and their dynamical evolution history. Therefore, these stellar fossils provide a unique window to learn about the early cosmic era at a high level of detail, which even the James Webb Space Telescope cannot reach. In this talk, I will briefly review the study of these ancient metal-poor stars, in particular, the so-called Carbon Enhanced Metal-Poor (CEMP) stars, which are predominant members in the low metallicity regime. I will also talk about how to find these stars and to characterize their astrophysical origins by decoding their abundance patterns and kinematics. Finally, I will present the latest understanding of the nucleosynthetic and dynamical accretion origins of the CEMP-no stars, a subset of the CEMP stars, which are thought to be the immediate descendants of the first stars.