This article revisits side-channel analysis from the standpoint of coding theory. On the one hand, the attacker is shown to apply an optimal decoding algorithm in order to recover the secret key from the analysis of the side-channel. On the other hand, the side-channel protections are presented as a coding problem where the information is mixed with randomness to weaken as much as possible the sensitive information leaked into the side-channel. Therefore, the field of side-channel analysis is viewed as a struggle between a coder and a decoder. In this paper, we focus on the main results obtained through this analysis. In terms of attacks, we discuss optimal strategy in various practical contexts, such as type of noise, dimensionality of the leakage and of the model, etc. Regarding countermeasures, we give a formal analysis of some masking schemes, including enhancements based on codes contributed via fruitful collaborations with Claude Carlet.