Non-coding RNAs (ncRNAs) are RNA molecules which are not translated into proteins. They are classified into two types based on their length, including short non-coding RNAs comprising microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). They play a role in gene regulation at various levels, ranging from epigenetic gene silencing to post-transcriptional modulation of mRNA stability. The ncRNAs contribute in the regulation of cell physiology and shape cellular functions. They play an important role in brain development and function, and are also associated with the pathogenesis of psychiatric disorders. Several ncRNAs including circRNAs, miRNAs and lncRNAs have been implicated in regulatory functions. Furthermore, they are believed to play a role in Alzheimer's disease and cancer. This book explores all the important aspects of the biochemistry of RNA. It presents researches and studies performed by experts across the globe. The extensive content of this book provides the readers with a thorough understanding of this topic.