Stevia is a non-caloric sweetener that is relatively new on the international market. It originates in the leaves of a South American plant. Because of that it’s marketed as a “100% natural” alternative to other non-caloric sweeteners.
There’s been some discussion about how natural it really is, as it’s extracted from the leaves using different solvents and goes through further chemical processes before it emerges as a white sweet powder.
Personally I’m no fan of sweeteners, regardless of their origin. They tend to maintain an addiction to sweets. I’ve never seen Stevia as “natural”. It’s purified from leaves and thus it’s no more natural than snorting cocaine (which is also purified from leaves).