Site-directed mutagenesis is a technique used in molecular biology for making precise and intentional changes to the DNA sequence of a gene of interest. It involves the use of specialized laboratory procedures and equipment, such as polymerase chain reaction (PCR) and restriction enzymes, to create specific mutations in the target gene. This technique is often used to investigate the function of specific regions or amino acids in a protein, and may also be applied in the development of new drug therapies or genetic engineering projects. Due to the technical complexity and specialized knowledge required, site-directed mutagenesis is typically performed by experienced molecular biologists or skilled technicians.