Root beer is so called because of its original main ingredients. Historically, it contained the sassafras root and a very small amount of alcohol. These were mixed together with combinations of other herbs, roots and berries.
In the 1800s, tea and beer were safer to drink than water because of sanitation reasons. The brewing process of tea and beer killed bacteria and made it healthier to drink than the water that was available. Small beers were very popular drinks at the time. These beers contained a small amount of alcohol, usually around 2 percent. The "beer" in the name root beer categorized the original formula as a small beer. This way, it could be marketed as safer to drink than water while still containing insignificant amounts of alcohol.
The first commercially successful root beer was introduced by Charles Hines in 1876. He created a specific blend of different herbs, roots and berries, specifically the sassafras root. He originally sold the drink as a dry mix packet of root tea to cure sicknesses. However, when he began bottling the drink in its liquid form, he changed the name to root beer as a marketing strategy. It instantly made the drink more popular and solidified its place in history.