Drug affinity refers to the strength of binding between a drug molecule and its target. There are several synonyms that are used interchangeably with drug affinity, including binding strength, drug-receptor interaction, and drug-target interaction. Another related term is potency, which refers to the concentration of a drug required to elicit a response. High drug affinity is desirable in drug development as it allows for lower dosages and fewer side-effects. Understanding the drug affinity is critical in designing drugs that are effective, safe and have a minimal binding to other targets, thereby reducing the risk of off-target effects.