"Analgesia is the loss of sensation of pain that results from an interruption in the nervous system pathway between sense organ and brain. An analgesic, or painkiller, is any member of the group of drugs used to achieve analgesia-relief from pain. Analgesics act in various ways on the peripheral and central nervous systems. They are distinct from Anesthetics which reversibly eliminate sensation. Analgesics serve to be an important component in Pain Management. Analgesics can be broadly divided into two groups: Non-opioid (also referred to as non-narcotic, peripheral, mild and antipyretic agents) and Opioids (also called narcotic, central or strong agents). Non-opiods and Opiods are further classified into several sub-categories. Non-opioid analgesics are pain medications for mild to moderate pain. Non-opioid drugs are classified into three categories: Salicylates, Nonsteroidial anti-inflammatory drugs (NSAIDs) and Acetaminophen. Aspirin is a kind of salicylate, used to treat mild to moderate pain, inflammation, fever, arthritis and reduce blood clotting. They may be taken alone for pain management, though they may also be taken in combination with opioids to relieve moderate to severe pain. An Opioid is any psychoactive chemical that resembles morphine or other opiates in its pharmacological effects. The analgesic effects of opioids are due to decreased perception of pain, decreased reaction to pain as well as increased pain tolerance. One of the main functions of opioids is to produce sedation and pain relief and they have been used for pain relief over thousands of years. Opiods are classified into three categories based on their opiate receptor activity: Opiod Agonist (used to treat moderate to severe pain), Mixed Opiod Angonist (Used to treat moderate to severe pain; not commonly used in dentistry; physical dependence to Buprenorphine is low and withdrawal is mild) and Opiod Antagonist (used to counteract the pharmacologic and reverse reactions of opiod agonists and mixed angonists and in the management of overdoses). "