This comprehensive review by Silvia Zecchi et al. focuses on the current state of electromagnetic interference (EMI) shielding composite materials, emphasizing their importance in preventing electromagnetic pollution and ensuring the proper functioning of electronic devices. The review covers the interaction between matter and microwaves, the principles of EMI shielding, and the fabrication techniques used to create these composites. It highlights the role of composite materials, which combine different materials to enhance EMI shielding effectiveness (EMI SE) through factors such as filler type, concentration, and matrix material. The review also discusses the properties of various fillers, including organic, inorganic, and hybrid fillers, and their impact on EMI SE. Additionally, it explores the performance of different composite materials in different frequency ranges, particularly in the microwave region from 1 GHz to 170 GHz. The review provides a detailed analysis of the shielding mechanisms, such as reflection, absorption, and internal multiple reflection, and the factors that influence these mechanisms. Finally, it presents a comprehensive overview of the latest advancements and challenges in EMI shielding composite materials, offering valuable insights for both experts and newcomers to the field.This comprehensive review by Silvia Zecchi et al. focuses on the current state of electromagnetic interference (EMI) shielding composite materials, emphasizing their importance in preventing electromagnetic pollution and ensuring the proper functioning of electronic devices. The review covers the interaction between matter and microwaves, the principles of EMI shielding, and the fabrication techniques used to create these composites. It highlights the role of composite materials, which combine different materials to enhance EMI shielding effectiveness (EMI SE) through factors such as filler type, concentration, and matrix material. The review also discusses the properties of various fillers, including organic, inorganic, and hybrid fillers, and their impact on EMI SE. Additionally, it explores the performance of different composite materials in different frequency ranges, particularly in the microwave region from 1 GHz to 170 GHz. The review provides a detailed analysis of the shielding mechanisms, such as reflection, absorption, and internal multiple reflection, and the factors that influence these mechanisms. Finally, it presents a comprehensive overview of the latest advancements and challenges in EMI shielding composite materials, offering valuable insights for both experts and newcomers to the field.