The NCBI Nucleotide database is a collection of genomic (genomic DNA or genomic RNA) and transcript (mRNA and non-coding RNA) sequences from numerous organisms.

The genomic sequences range from short fragments representing individual genes and other small genomic regions to completely assembled chromosomes.  The number of genomic sequence records in the database differs from organism to organism. For some organisms, there will only be partial sequences of a limited number of genes such as those routinely sequenced in phylogenetic and/or population studies.  For others, including human and other medically important organisms, there may be more than one assembly of the entire organism’s genome.  For example, there can be more than 100 complete genomes for a single bacterial species.

Read more about how to find all Nucleotide records belonging to a genomic assembly.