This chapter presents the main Side-Channel Attacks, a kind of hardware cryptanalytic techniques which exploits the physical behavior of an IC to extract secrets implied in cryptographic operations. We show in this chapter the main modern concepts about Side Channel Attacks (Simple and Differential Power Analysis) and how they can be deployed on FPGA architecture. We give also a set of details on platform and equipment needed to conduct such type of experiments. Then we propose a discussion about the leakage model of digital IC, comprising FPGA, and we illustrate these attacks on a set of real case study. We conclude this chapter by giving the latest information and link toward new efficient Side Channel Attacks.