Advil is a nonsteroidal anti-inflammatory drug (NSAID) that is commonly used to relieve pain and reduce fever. The active ingredient in Advil is ibuprofen, which was first discovered in the 1960s by researchers at Boots Pure Drug Company in England [1]. Ibuprofen was initially used to treat rheumatoid arthritis and other inflammatory conditions. In the 1970s, ibuprofen was approved for use in the United States and became available as a prescription drug [2].

In the 1980s, the patent for ibuprofen expired, and several companies began to manufacture and sell the drug under different brand names, including Advil [1]. Advil was first introduced in the United States in 1984 by Whitehall-Robins Healthcare, which is now a subsidiary of Pfizer [2]. Advil quickly became popular due to its effectiveness in relieving pain and reducing fever, as well as its availability over the counter.

Advil's popularity also grew due to the Tylenol murders in 1982. The Tylenol murders were a series of deaths caused by cyanide-laced Tylenol capsules [3]. The incident led to a widespread fear of over-the-counter medications and prompted many people to switch to Advil and other pain relievers that were perceived as safer.

In conclusion, Advil was created in response to the expiration of the patent for ibuprofen and was introduced to the market in 1984 by Whitehall-Robins Healthcare. Advil's popularity grew due to its effectiveness in relieving pain and reducing fever, as well as the Tylenol murders in 1982.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ADVIL
[2] https://www.bbc.com/news/health-34798438
[3] https://www.pbs.org/newshour/health/tylenol-murders-1982