The pragmatic species concept for Bacteria and Archaea is ultimately based on DNA-DNA hybridization (DDH), a method known to be tedious. The GGDC is a state-of-the-art in silico method for genome-to-genome comparison, thus reliably mimicking conventional DDH, except for its pitfalls. The method implemented in the GGDC was shown to outperform ANI, the “Average Nucleotide Identity” approach.