E3 ligases are enzymes that play a crucial role in the process of ubiquitination, a post-translational modification that targets proteins for degradation by the proteasome or regulates their activity, localization, or interactions with other proteins. E3 ligases are responsible for recognizing specific protein substrates and catalyzing the transfer of ubiquitin molecules onto them. There are two main classes of E3 ligases: HECT (homologous to E6AP carboxyl terminus) ligases and RING (really interesting new gene) ligases. Dysregulation of E3 ligases has been implicated in various diseases, including cancer, neurodegenerative disorders, and autoimmune diseases, making them potential targets for therapeutic intervention. Research in the field of E3 ligases aims to understand their mechanisms of action, substrate specificity, and regulation, as well as to develop novel strategies for modulating their activity for therapeutic purposes.