Non-coding RNAs with lengths exceeding 200 nucleotides are commonly dubbed as long non-coding RNAs (lncRNAs), which have been found to perform various functions in a wide variety of important biological processes. To better understand their functional significance, Professor ZHANG Zhang and his team at Beijing Institute of Genomics, Chinese Academy of Sciences, performed systematic investigations to classify lncRNAs into different groups. The team summarizes classification methods of lncRNAs according to their different features, including their genome location and context, exerted effect on DNA sequences, mechanism of functioning, and targeting mechanism. It is believed that the classifications of lncRNAs are of fundamental importance for lncRNA studies, helpful for further investigation of specific groups of lncRNA, for generation of new hypothesis based on different lncRNA groups and for exploration of lncRNA underlying functional mechanisms. The study has been recently published on RNA Biology. Length distribution of lncRNAs in human and mouse. (Imaged by Prof. ZHANG’s group) Contact: Prof. ZHANG Zhang Email: zhangzhang@big.ac.cn