Light Elements in Main Sequence Stars: Li, Be, B, C, O

The abundances of the {\it rare} light elements, Li, Be, and B, provide clues about stellar structure and evolution, about Galactic evolution and about their nucleosynthesis, including production during the Big Bang. The abundances of the {\it abundant} light elements, C and O, reveal information about the chemical history of the Galaxy and the mass spectrum of early generations of stars.