Potassium nitrate, KNO3, is a chemical with many applications, many taking use of its property as an oxidizing agent and a fertilizer. It has been known since antiquity as saltpeter and other folk names, often under manure, and as one of the principal ingredients in black gunpowder. It is used as a preservative for sausage and other cured meats.
As opposed to ammonium nitrate, it is not easily explosive by itself, and, even with additives, only as a low explosive. Materials soaked in potassium nitrate solution and dried will burn quickly, and are the most common form of burning fuse.
While it is still collected from the wild for traditional culture, most industrial potassium nitrate is made from the double decomposition of sodium nitrate and sodium chloride. Sodium nitrate is mined from massive deposits on the western coast of South America.
Contrary to urban legend, doses below the level of outright toxicity have no effect on sexual performance.