According to many physicists, several aspects of the laws of nature, the constants, and the cosmic boundary conditions are fine-tuned for life: had they been slightly different, life would not have existed. Here I review the claimed instances of fine-tuning and some of the criticism that has been levelled against the fine-tuning considerations. I also discuss in which sense, if any, fine-tuned parameters may qualify as improbable. Finally, I review the naturalness criterion of theory choice and discuss how violations of naturalness may be regarded as relevant to the discussion about fine-tuning for life.