The bio2db mainly provides the databases for genome sequences, comparative genomic analyses data, and bioinformatics tools, et al. These databases will be continuously updated and more new data will be generated and collected for comparative and functional genomics analysis in future. We welcome the users to browser, search, and download the data from our databases. In addition, we also encourage the users can submit the data to our database. Please contact us by email if you have any questions or comments for these databases, and we will respond in a timely manner.