Multiferroics are materials that exhibit both ferromagnetism and ferroelectricity, often along with ferroelasticity. This paper reviews the microscopic mechanisms that enable the coexistence of these properties and discusses various methods to combine them in a single material. It highlights the role of d-state occupation in transition metal perovskites, the significance of spiral magnetic structures, and a novel mechanism of ferroelectricity arising from site-centred and bond-centred charge ordering. The paper also examines specific materials like magnetite (Fe₃O₄) and discusses the challenges in understanding the microscopic nature of ferroelectricity in these systems. The paper begins by noting that the combination of magnetic and ferroelectric properties was first explored in the 1960s, with significant progress occurring around 2001-2003 due to advancements in thin film technology and the discovery of new multiferroic systems. The main challenge lies in the coexistence of these properties, as conventional systems often exclude one from the other. However, several materials have been found to exhibit both properties. The paper discusses two main approaches to achieving multiferroicity: independent magnetic and ferroelectric subsystems, and perovskites. In perovskites, the presence of transition metal ions with empty d-shells is crucial for ferroelectricity, while magnetic ions with filled d-shells can lead to magnetism. However, the mutual exclusion of these properties in perovskites is not absolute, as seen in materials like BiFeO₃ and BiMnO₃, where the A-ion (e.g., Bi³⁺) plays a key role in ferroelectricity. The paper also explores the role of lone pairs in Bi and Pb perovskites, which contribute to ferroelectricity. It discusses hexagonal manganites, which exhibit high transition temperatures and ferroelectricity due to structural distortions. The paper further examines charge ordering in magnetic systems, where site-centred and bond-centred charge ordering can lead to ferroelectricity. It also highlights the possibility of generating ferroelectricity through magnetic ordering, particularly in materials with spiral magnetic structures, where the spin rotation axis does not align with the wave vector of the spiral, leading to a net polarization. The paper concludes that the study of multiferroics is a rich and complex field with many open questions, and that further research is needed to fully understand the mechanisms behind these materials.Multiferroics are materials that exhibit both ferromagnetism and ferroelectricity, often along with ferroelasticity. This paper reviews the microscopic mechanisms that enable the coexistence of these properties and discusses various methods to combine them in a single material. It highlights the role of d-state occupation in transition metal perovskites, the significance of spiral magnetic structures, and a novel mechanism of ferroelectricity arising from site-centred and bond-centred charge ordering. The paper also examines specific materials like magnetite (Fe₃O₄) and discusses the challenges in understanding the microscopic nature of ferroelectricity in these systems. The paper begins by noting that the combination of magnetic and ferroelectric properties was first explored in the 1960s, with significant progress occurring around 2001-2003 due to advancements in thin film technology and the discovery of new multiferroic systems. The main challenge lies in the coexistence of these properties, as conventional systems often exclude one from the other. However, several materials have been found to exhibit both properties. The paper discusses two main approaches to achieving multiferroicity: independent magnetic and ferroelectric subsystems, and perovskites. In perovskites, the presence of transition metal ions with empty d-shells is crucial for ferroelectricity, while magnetic ions with filled d-shells can lead to magnetism. However, the mutual exclusion of these properties in perovskites is not absolute, as seen in materials like BiFeO₃ and BiMnO₃, where the A-ion (e.g., Bi³⁺) plays a key role in ferroelectricity. The paper also explores the role of lone pairs in Bi and Pb perovskites, which contribute to ferroelectricity. It discusses hexagonal manganites, which exhibit high transition temperatures and ferroelectricity due to structural distortions. The paper further examines charge ordering in magnetic systems, where site-centred and bond-centred charge ordering can lead to ferroelectricity. It also highlights the possibility of generating ferroelectricity through magnetic ordering, particularly in materials with spiral magnetic structures, where the spin rotation axis does not align with the wave vector of the spiral, leading to a net polarization. The paper concludes that the study of multiferroics is a rich and complex field with many open questions, and that further research is needed to fully understand the mechanisms behind these materials.