Bacterial DNA is not confined to a nucleus. However, it is often confined to a particular region of the cell, called the nuclear body or nucleoid (this region is not bound by a membrane).
Bacteria carry the majority of their DNA in a single circular chromosome. As bacteria have only one copy of this chromosome, they are haploid (not diploid like most animal cells).
Some bacteria carry part of their genomes in plasmids.
Plasmids are sections of DNA which are not part of the chromosome and are able to replicate and be transmitted independently. Plasmids are important in maintaining genetic variation amongst bacterial cells.