RNA interference (RNAi) is a biological process that regulates gene expression by silencing specific messenger RNA (mRNA) molecules. This occurs when small RNA molecules, such as small interfering RNA (siRNA) or microRNA (miRNA), bind to complementary mRNA sequences, preventing them from being translated into proteins. This mechanism is crucial for various cellular functions, including development, defense against viruses, and maintaining cellular homeostasis. Researchers are exploring RNAi for potential therapeutic applications, such as targeting disease-causing genes in conditions like cancer and genetic disorders, making it a significant area of study in molecular biology.