Book excerpt: Discoveries from the past decades revealed that RNA molecules are much more than inert intermediates between the coding DNA sequences and their functional products, proteins. Today, RNAs are recognized as active regulatory molecules influencing gene expression, chromatin organization and genome stability, thus impacting all aspects of plant life including development, growth, reproduction and stress tolerance. Innovations in methodologies, the expanding application of next-generation sequencing technologies, and the creation of public datasets and databases have exposed a new universe of RNA-based mechanisms and led to the discovery of new families of non-coding RNAs, uncovered the large extent of alternative splicing events, and highlighted the potential roles of RNA modifications and RNA secondary structures. Furthermore, considerable advances have been made in identifying RNA-binding and processing factors involved in the synthesis and maturation of different forms of RNA molecules as well as in RNA processing, biochemical modifications or degradation. This Research Topic showcases the broad biological significance of RNAs in plant systems and contains eight original research articles, one review and four mini-reviews, covering various RNA-based mechanisms in higher plants. Emerging new technologies and novel multidisciplinary approaches are empowering the scientific community and will expectedly bring novel insights into our understanding of the mechanisms through which RNA is regulated and regulates biological processes in plant cells.