This question is the result of the modern era using the blanket word ray-tracing to denote every similar technique as it's based off of it. Just wanted to give a more historical answer if anybody is interested.
As lightxbulb said, historically, Turner Whitted was the first person to come up with the raytracing technique but it only had a limited number of rays. Reflection/Refraction and these secondary rays got terminated when they hit a diffuse surface since no GI rays were shot.
The problem of Global Illumination is recursive and as you might've guessed it requires many many rays. The math wasn't that complex and sophisticated in pure raytracing. Then later on, Radiosity method was introduced by Goral which accounted for GI but only for diffuse surfaces using the Finite element method. This was a major step ahead and helped in laying the foundation for pathtracing.
After that Pathtracing got introduced by Kajiya which accounted for all types of surfaces, He used Monte-Carlo Integration to solve the recursive integral related to the GI problem.
As time went by, the word raytracing somehow overshadowed the other words in this field. And recently, with NVIDIA dishing out their RTX technology pretty much sealed the fact. So raytracing in today's era doesn't necessarily mean whitted-style raytracing which was the original raytracing.