The article discusses the organization and functions of the endoplasmic reticulum (ER)–mitochondria contact sites. These contacts, which are 10–30 nm wide, are stable and can be observed using electron microscopy and fluorescence microscopy. The ER–mitochondria junction plays a crucial role in coordinating the functions of these organelles, including lipid synthesis, Ca²⁺ signaling, mitochondrial biogenesis, and intracellular trafficking. The ER–mitochondria contact sites are involved in lipid exchange during biosynthesis, where enzymes involved in lipid synthesis are localized to both the ER and mitochondrial membranes. The ERMES complex, composed of Mmm1, Mdm10, Mdm12, and Mdm34, is a tethering complex that facilitates lipid exchange and may also mediate other functions at these sites. The ER–mitochondria junction is also important for mitochondrial division, where it marks the sites of division machinery recruitment and constricted regions of mitochondria. The ER and mitochondria maintain contact during dynamic movements, and this contact is essential for coordinated movement along microtubules. Additionally, the ER–mitochondria junction regulates Ca²⁺ transfer, which is crucial for mitochondrial function, division, and apoptosis. The article concludes by highlighting the potential significance of ER–mitochondria contacts in disease, particularly neurodegenerative disorders.The article discusses the organization and functions of the endoplasmic reticulum (ER)–mitochondria contact sites. These contacts, which are 10–30 nm wide, are stable and can be observed using electron microscopy and fluorescence microscopy. The ER–mitochondria junction plays a crucial role in coordinating the functions of these organelles, including lipid synthesis, Ca²⁺ signaling, mitochondrial biogenesis, and intracellular trafficking. The ER–mitochondria contact sites are involved in lipid exchange during biosynthesis, where enzymes involved in lipid synthesis are localized to both the ER and mitochondrial membranes. The ERMES complex, composed of Mmm1, Mdm10, Mdm12, and Mdm34, is a tethering complex that facilitates lipid exchange and may also mediate other functions at these sites. The ER–mitochondria junction is also important for mitochondrial division, where it marks the sites of division machinery recruitment and constricted regions of mitochondria. The ER and mitochondria maintain contact during dynamic movements, and this contact is essential for coordinated movement along microtubules. Additionally, the ER–mitochondria junction regulates Ca²⁺ transfer, which is crucial for mitochondrial function, division, and apoptosis. The article concludes by highlighting the potential significance of ER–mitochondria contacts in disease, particularly neurodegenerative disorders.