Molecular biology techniques have had an impact on microbial taxonomy since the discovery of Archaea based on rRNA fingerprinting. Now, the development of DNA sequencing technology and bioinformatics has enabled us to use whole genome sequences in prokaryotic taxonomy including with previously uncultivated lineages. In fact, the genome taxonomy database (GTDB) is one of the most reliable databases with which to identify the taxonomy of individual microbes including uncultured lineages based on genomic information. However, the International Code of Nomenclature of Prokaryotes does not officially accept genome-based taxonomy, and a genome-based taxonomy scheme called the SeqCode Initiative has been launched. Here, I summarize the history of the impact of molecular biology techniques and subsequent genomic information on prokaryotic taxonomy since the discovery of Archaea (archaebacteria), and the recent changes in microbial taxonomy to understand the current situation.