RNA interference (RNAi) is a molecular mechanism that plays a critical role in regulating gene expression. It involves the use of small RNA molecules, mostly siRNAs and miRNAs, to selectively degrade complementary mRNA molecules, thereby reducing protein expression. Due to its importance in gene regulation and various applications, there are several other terms that are often used interchangeably with RNA interference. These include RNA silencing, post-transcriptional gene silencing, gene knockdown, and gene silencing. All these terms refer to the same basic mechanism of gene regulation and are used in different contexts, depending on the specific application and scientific field.