Genome is an entirety of the hereditary information of a particular organism. This information is coded in DNA (in RNA for certain viruses). Genome thus comprises both protein-coding and non-coding DNA or RNA. The genome of many organisms (including human) has been completely sequenced.
In case of eukaryotic organisms it is possible to distinguish nuclear genome and extranuclear genome (i.e. DNA sequences of semiautonomous organelles - mitochondria or plastids).