MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression by binding to target mRNAs, leading to translational repression or mRNA degradation. Discovered over 30 years ago in Caenorhabditis elegans, miRNAs have since been found in humans and are believed to regulate one-third of the genome. They are involved in various biological processes and have been linked to numerous diseases, including cancer, metabolic disorders, and viral infections. miRNAs are produced through a biogenesis pathway involving Drosha and Dicer enzymes, which process the primary miRNA transcript into a mature miRNA. The mature miRNA is then loaded into the RNA-induced silencing complex (RISC), where it directs the complex to target mRNAs. Alternative pathways for miRNA biogenesis also exist, such as the mirtron class. miRNAs play critical roles in development, tissue homeostasis, and disease progression. They are being explored as diagnostic markers and therapeutic targets, with miRNA-based therapies under development for conditions like cancer and hepatitis C. miRNAs are also found in extracellular fluids, such as plasma, where they can be used for diagnostic purposes. Advances in genome editing technologies, including CRISPR/Cas, have opened new avenues for miRNA-related research and therapy. Overall, miRNAs are a key component of gene regulation and have significant implications for both basic research and clinical applications.MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression by binding to target mRNAs, leading to translational repression or mRNA degradation. Discovered over 30 years ago in Caenorhabditis elegans, miRNAs have since been found in humans and are believed to regulate one-third of the genome. They are involved in various biological processes and have been linked to numerous diseases, including cancer, metabolic disorders, and viral infections. miRNAs are produced through a biogenesis pathway involving Drosha and Dicer enzymes, which process the primary miRNA transcript into a mature miRNA. The mature miRNA is then loaded into the RNA-induced silencing complex (RISC), where it directs the complex to target mRNAs. Alternative pathways for miRNA biogenesis also exist, such as the mirtron class. miRNAs play critical roles in development, tissue homeostasis, and disease progression. They are being explored as diagnostic markers and therapeutic targets, with miRNA-based therapies under development for conditions like cancer and hepatitis C. miRNAs are also found in extracellular fluids, such as plasma, where they can be used for diagnostic purposes. Advances in genome editing technologies, including CRISPR/Cas, have opened new avenues for miRNA-related research and therapy. Overall, miRNAs are a key component of gene regulation and have significant implications for both basic research and clinical applications.