Path Tracing
Is an [see page 13, alternative] to advanced-ray-tracing which both shoots many rays per pixel, but only one ray directed randomly for each intersection, until a light source is hit (or TERMINATE). Once this is done we use the angles of the intersection and the material properties to determine the color for that pixel.
This technique is generally dependent on the number of rays we send out per-pixel, with the larger the number leading to a better approximation of the actual scene. Low ray counts lead to a more noisy image.
A general performance improvement for this approach is to use a low ray-per-pixel count and then to [see page 14, filter] the produced image to denoise it.