Reference genomes, annotations of genomic regions and associated gene products (transcripts or proteins), and mappings between molecule identifiers are essential for placing statistical and bioinformatic results into biological perspective. These needs are partly addressed by the Bioconductor annotation data repository, which provides 894 prebuilt standardized annotation packages for use with common model organisms as well as other organisms. Each of the packages presents its data through a standard interface using defined Bioconductor classes, including classes for whole-genome sequences (BSgenome), gene model or transcript databases (TxDb) derived from UCSC (University of California, Santa Cruz) tracks or BioMart annotations, and identifier cross-references from the US National Center for Biotechnology Information, or NCBI (org). There are also facilities for users to create their own annotation packages.
