Plasmid is typically a small circular DNA strand in the cytoplasm of a bacterium or protozoan. It is a genetic structure in a cell that can replicate independently of the chromosomes. They are commonly used in recombinant DNA technology. Plasmids naturally exist in bacterial cells, and they also occur in some eukaryotes. Often, the genes carried in plasmids provide bacteria with genetic advantages, such as antibiotic resistance.

Source: ForumIAS