This chapter covers the renormalization of Quantum Electrodynamics (QED) to address the divergences found in loop corrections, such as the electron self-energy. It begins by introducing methods of regularization, like dimensional regularization. The conceptual basis is built upon the Renormalization Group (RG) flow and beta functions, illustrated using \( \lambda \phi ^4\) theory, which leads to the concept of a running coupling. The general procedure for renormalization is detailed, emphasizing the use of counterterms to define a renormalizable theory. Finally, the chapter applies this formalism to the one-loop renormalization of QED, treating the divergences related to the electron mass renomalization, wavefunction renomalization, and vertex renomalization.