Questions about algorithms whose behaviour is determined not only by its input but also by a source of random numbers.
Use with category tag algorithms and, depending on the problem you are solving, optimization, search-problem or decision-problem. Other topical tags that may apply are graphs or sorting, among many others.
Popular examples include variants of Quicksort that choose the pivot randomly, and probabilistic algorithms such as Miller-Rabin primality test.
Related, but distinct: probabilistic-algorithms -- read more here.