Restriction enzymes are proteins that act like molecular scissors, cutting DNA at specific sequences. They are naturally found in bacteria, where they serve as a defense mechanism against viruses by slicing up foreign DNA. Each enzyme recognizes a particular sequence of nucleotides, allowing scientists to manipulate DNA for various applications. These enzymes are essential tools in genetic engineering and molecular biology. Researchers use them to create recombinant DNA, which involves combining DNA from different sources. This process is crucial for cloning, gene therapy, and the production of genetically modified organisms (GMOs).