SILVA is a comprehensive, quality-controlled web resource for up-to-date aligned ribosomal RNA (rRNA) gene sequences from the Bacteria, Archaea and Eukaryota domains alongside supplementary online services. In addition to data products, SILVA provides various online tools such as alignment and classification, phylogenetic tree calculation and viewer, probe/primer matching, and an amplicon analysis pipeline. With every full release a curated guide tree is provided that contains the latest taxonomy and nomenclature based on multiple references. The SILVA project published its initial release in 2007 and has become a mature resource of rRNA sequence data and is acknowledged as an ELIXIR Core Data Resource which “are a set of European data resources of fundamental importance to the wider life-science community and the long-term preservation of biological data.” SILVA is also part of the German Network for Bioinformatics Infrastructure (de.NBI) and ELIXIR Germany.