Small molecule inhibitors refer to a class of compounds that can bind to specific target proteins, such as enzymes or receptors, and block their activity. These small molecules work by interfering with the normal function of these proteins, often by occupying the same binding site where an endogenous substrate would normally bind. By doing so, they can modulate cellular processes, inhibit the growth of cancer cells or prevent the replication of viruses. Small molecule inhibitors are widely used as drugs and have become increasingly important in drug discovery due to their ability to target specific proteins with high precision.