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, allowing bacteria to adapt to their environment. Scientists use plasmids in genetic engineering and biotechnology. By inserting specific genes into plasmids, researchers can create genetically modified organisms (GMOs) or produce proteins like insulin. This technique is essential for advancements in medicine, agriculture, and research, making plasmids valuable tools in the field of molecular biology.