Restriction enzymes, also known as restriction endonucleases, are proteins that cut 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 for precise cuts. These enzymes are widely used in molecular biology for various applications, including cloning, gene editing, and DNA analysis. By cutting DNA at specific sites, researchers can manipulate genetic material, insert new genes, or create recombinant DNA, which is essential for advancements in genetics and biotechnology.