Plasmids are small, circular pieces of DNA found in many bacteria and some archaea. They exist independently of the chromosomal DNA and can replicate on their own. Plasmids often carry genes that provide beneficial traits, such as antibiotic resistance, which can help bacteria survive in challenging environments. In addition to bacteria, plasmids are also used in genetic engineering and biotechnology. Scientists can insert specific genes into plasmids to create recombinant DNA, which can then be introduced into host cells for research or therapeutic purposes. This technique is essential for producing proteins, vaccines, and genetically modified organisms (GMOs).