Break-out reactions from the CNO cycles

This paper summarizes our present understanding of the nucleosynthesis and energy generation in the carbon-nitrogen-oxygen (CNO) cycles and the influence and consequences of possible break-out reactions from the CNO range. It gives an overview of the present status of the experimental and theoretical reaction rates involved, as well as the stellar conditions at which the CNO cycle occurs. Besides the role of the CNO cycles and break-out reactions in stellar hydrogen burning, the paper discusses possible CNO depletion processes by neutron, alpha and heavy-ion induced reactions in post-main-sequence star environments.