The article discusses the emergence of 2D magnetic materials and their impact on the field of van der Waals heterostructures. It highlights the recent discovery of atomically-thin magnetic crystals, which has expanded the family of 2D materials and opened new avenues for exploring magnetic states in two dimensions. The authors focus on two extensively studied systems: semiconducting CrI$_3$ and metallic Fe$_3$GeTe$_2$. They present the differences between magnetic states in 2D materials and bulk crystals, emphasizing the role of spin dimensionality in determining the critical behavior of magnetic systems. The article also reviews experimental techniques used to study these materials, including magneto-optical Kerr effect and magnetic circular dichroism. Additionally, it explores the potential of 2D magnets in heterostructures, such as magnetic tunnel junctions, and discusses the possibility of electrostatic control of magnetism through gating. The overall aim is to provide a comprehensive overview of the current state and future prospects of 2D magnets and their applications in van der Waals heterostructures.The article discusses the emergence of 2D magnetic materials and their impact on the field of van der Waals heterostructures. It highlights the recent discovery of atomically-thin magnetic crystals, which has expanded the family of 2D materials and opened new avenues for exploring magnetic states in two dimensions. The authors focus on two extensively studied systems: semiconducting CrI$_3$ and metallic Fe$_3$GeTe$_2$. They present the differences between magnetic states in 2D materials and bulk crystals, emphasizing the role of spin dimensionality in determining the critical behavior of magnetic systems. The article also reviews experimental techniques used to study these materials, including magneto-optical Kerr effect and magnetic circular dichroism. Additionally, it explores the potential of 2D magnets in heterostructures, such as magnetic tunnel junctions, and discusses the possibility of electrostatic control of magnetism through gating. The overall aim is to provide a comprehensive overview of the current state and future prospects of 2D magnets and their applications in van der Waals heterostructures.