Used primarily in medical and research settings to study the function of the nervous system, particularly the role of neurotransmitters. It is often applied in experiments to understand synaptic transmission and the effects of acetylcholine on various tissues, such as muscle and cardiac cells. In clinical contexts, it serves as a diagnostic tool to assess certain neurological conditions by evaluating the responsiveness of receptors. Additionally, it is utilized in ophthalmology during cataract surgery to induce rapid miosis, aiding in the procedure. Its role in mimicking natural acetylcholine makes it valuable for both therapeutic and investigative purposes.