The article provides an overview of the current understanding of long noncoding RNAs (lncRNAs), highlighting their genomic contexts, biological functions, and mechanisms of action. LncRNAs, which are transcripts longer than 200 nucleotides, have gained significant attention due to their involvement in various developmental processes and diseases. Despite the widespread interest, the mechanisms by which lncRNAs function remain largely unknown, and the extent of their biological significance is still debated. The authors discuss the historical context of lncRNA research, including the discovery of pervasive transcription and the C-value enigma, and review the classification of lncRNAs based on their genomic locations. They also explore the roles of lncRNAs in epigenetic regulation, such as X chromosome inactivation and genomic imprinting, as well as their involvement in developmental processes and cancer. The article emphasizes the complex mechanisms by which lncRNAs exert their effects, including their interactions with protein factors, recruitment of chromatin-modifying complexes, and influence on transcription and mRNA processing. The authors conclude by discussing the challenges and future directions in lncRNA research, emphasizing the need for further studies to elucidate the functions and mechanisms of these molecules.The article provides an overview of the current understanding of long noncoding RNAs (lncRNAs), highlighting their genomic contexts, biological functions, and mechanisms of action. LncRNAs, which are transcripts longer than 200 nucleotides, have gained significant attention due to their involvement in various developmental processes and diseases. Despite the widespread interest, the mechanisms by which lncRNAs function remain largely unknown, and the extent of their biological significance is still debated. The authors discuss the historical context of lncRNA research, including the discovery of pervasive transcription and the C-value enigma, and review the classification of lncRNAs based on their genomic locations. They also explore the roles of lncRNAs in epigenetic regulation, such as X chromosome inactivation and genomic imprinting, as well as their involvement in developmental processes and cancer. The article emphasizes the complex mechanisms by which lncRNAs exert their effects, including their interactions with protein factors, recruitment of chromatin-modifying complexes, and influence on transcription and mRNA processing. The authors conclude by discussing the challenges and future directions in lncRNA research, emphasizing the need for further studies to elucidate the functions and mechanisms of these molecules.