Long noncoding RNAs (lncRNAs) have become a focus of biological research due to their potential role in gene regulation. Despite their abundance in the genome, the mechanisms by which lncRNAs function remain poorly understood. While many lncRNAs are transcribed from non-coding regions, their biological significance is still debated. Some well-studied lncRNAs have provided insights into their functions, but the classification and mechanisms of action are not yet fully established. The field of lncRNA research is rooted in the long-standing interest in genome evolution and function. Recent advances in genomic technologies have enabled the discovery of numerous lncRNAs, but the functional roles of many remain unclear. LncRNAs are found in various organisms, with significant discoveries in plants, fungi, and invertebrates. However, the review focuses on mammalian examples. The study of lncRNAs has revealed their involvement in processes such as X chromosome inactivation, genomic imprinting, and cancer. LncRNAs can act as regulators of gene expression, either by recruiting epigenetic factors or by influencing transcriptional processes. Some lncRNAs may also play roles in nuclear compartments and post-transcriptional regulation, such as affecting mRNA processing, stability, and translation. The mechanisms by which lncRNAs function are still being explored, and while some lncRNAs have been shown to have biological roles, many remain to be characterized. The field of lncRNA research is still in its early stages, and further studies are needed to fully understand their functions and potential applications.Long noncoding RNAs (lncRNAs) have become a focus of biological research due to their potential role in gene regulation. Despite their abundance in the genome, the mechanisms by which lncRNAs function remain poorly understood. While many lncRNAs are transcribed from non-coding regions, their biological significance is still debated. Some well-studied lncRNAs have provided insights into their functions, but the classification and mechanisms of action are not yet fully established. The field of lncRNA research is rooted in the long-standing interest in genome evolution and function. Recent advances in genomic technologies have enabled the discovery of numerous lncRNAs, but the functional roles of many remain unclear. LncRNAs are found in various organisms, with significant discoveries in plants, fungi, and invertebrates. However, the review focuses on mammalian examples. The study of lncRNAs has revealed their involvement in processes such as X chromosome inactivation, genomic imprinting, and cancer. LncRNAs can act as regulators of gene expression, either by recruiting epigenetic factors or by influencing transcriptional processes. Some lncRNAs may also play roles in nuclear compartments and post-transcriptional regulation, such as affecting mRNA processing, stability, and translation. The mechanisms by which lncRNAs function are still being explored, and while some lncRNAs have been shown to have biological roles, many remain to be characterized. The field of lncRNA research is still in its early stages, and further studies are needed to fully understand their functions and potential applications.