This review discusses the diverse cellular functions of long noncoding RNAs (lncRNAs) in development and disease. LncRNAs, which are transcribed by Polymerase II and lack protein-coding potential, have been found to play crucial roles in gene regulation, chromatin structure, and genome organization. They can interact with various proteins, including histone-modifying complexes, transcription factors, and chromatin remodelers, to regulate gene expression and chromatin accessibility. LncRNAs are involved in processes such as differentiation, lineage choice, organogenesis, and tissue homeostasis, and are also implicated in pathological conditions like cancer and cardiovascular disease. The review highlights specific examples of lncRNAs and their functions, including their roles in imprinting, X-chromosome inactivation, and the regulation of gene expression in different cell types. Additionally, it discusses the potential of lncRNAs as biomarkers and therapeutic targets in diseases such as cancer and cardiovascular disease. The review emphasizes the importance of understanding the complex mechanisms by which lncRNAs function to advance the field of noncoding RNA biology and its applications in medicine.This review discusses the diverse cellular functions of long noncoding RNAs (lncRNAs) in development and disease. LncRNAs, which are transcribed by Polymerase II and lack protein-coding potential, have been found to play crucial roles in gene regulation, chromatin structure, and genome organization. They can interact with various proteins, including histone-modifying complexes, transcription factors, and chromatin remodelers, to regulate gene expression and chromatin accessibility. LncRNAs are involved in processes such as differentiation, lineage choice, organogenesis, and tissue homeostasis, and are also implicated in pathological conditions like cancer and cardiovascular disease. The review highlights specific examples of lncRNAs and their functions, including their roles in imprinting, X-chromosome inactivation, and the regulation of gene expression in different cell types. Additionally, it discusses the potential of lncRNAs as biomarkers and therapeutic targets in diseases such as cancer and cardiovascular disease. The review emphasizes the importance of understanding the complex mechanisms by which lncRNAs function to advance the field of noncoding RNA biology and its applications in medicine.