And we can find as many as 20 plasmids inside a single cell. Now, a plasmid is a relatively small, naturally occurring circular DNA that exists inside the cell in addition to that cell's main DNA main genome. Now, a plasmid is a circular, double stranded DNA molecule. And by circular, we simply mean it does not have a beginning and it doesn't have an end. Now, the plasmid is able to replicate by itself independently of that main genomes replication process. And the entire purpose of this plasmid is to basically contain these special genes that gives the cell special abilities.