This review article focuses on the role of exosomes, particularly their microRNA (miRNA) content, in cell-to-cell communication and disease progression. Exosomes are nano-sized vesicles released from various cell types, containing mRNAs and miRNAs that can be taken up by neighboring or distant cells, modulating recipient cells. The article highlights the active sorting mechanism of exosomal miRNAs, which differ from those in the parent cells, and discusses the functions of these miRNAs in recipient cells. Key mechanisms of exosome formation and secretion, as well as their trafficking and internalization, are also covered. The review further explores the sorting mechanisms of exosomal miRNAs, including the nSMase2-dependent pathway, miRNA motif and sumoylated hnRNPs-dependent pathway, 3'-end of the miRNA sequence-dependent pathway, and the miRISC-related pathway. The functions of exosomal miRNAs, both conventional and novel, are discussed, emphasizing their roles in gene regulation and immune responses. Finally, the potential applications of exosomes and exosomal miRNAs in clinical settings, such as diagnostics and gene therapy, are highlighted, along with the challenges and future directions in this field.This review article focuses on the role of exosomes, particularly their microRNA (miRNA) content, in cell-to-cell communication and disease progression. Exosomes are nano-sized vesicles released from various cell types, containing mRNAs and miRNAs that can be taken up by neighboring or distant cells, modulating recipient cells. The article highlights the active sorting mechanism of exosomal miRNAs, which differ from those in the parent cells, and discusses the functions of these miRNAs in recipient cells. Key mechanisms of exosome formation and secretion, as well as their trafficking and internalization, are also covered. The review further explores the sorting mechanisms of exosomal miRNAs, including the nSMase2-dependent pathway, miRNA motif and sumoylated hnRNPs-dependent pathway, 3'-end of the miRNA sequence-dependent pathway, and the miRISC-related pathway. The functions of exosomal miRNAs, both conventional and novel, are discussed, emphasizing their roles in gene regulation and immune responses. Finally, the potential applications of exosomes and exosomal miRNAs in clinical settings, such as diagnostics and gene therapy, are highlighted, along with the challenges and future directions in this field.