siRNA, or small interfering RNA, is a type of RNA molecule that plays a crucial role in the regulation of gene expression. It is typically about 20-25 nucleotides long and works by binding to messenger RNA (mRNA) molecules, leading to their degradation. This process helps to silence specific genes, preventing them from being translated into proteins. Researchers utilize siRNA in various fields, including molecular biology and medicine, to study gene function and develop targeted therapies. By introducing siRNA into cells, scientists can selectively inhibit the expression of genes associated with diseases, offering potential treatments for conditions like cancer and viral infections.