  Ant Colony Optimization algorithm is a magnificent heuristics technique based
on the behavior of ants. Parallel computing is a means to achieve the desired
results in commensurable execution time. Parallelization of Ant Colony
Optimization is utilized to solve large and complex problems. This paper
discusses a review of different parallelization approaches for Ant Colony
Optimization and its various applications. Parallel Ant Colony Optimization has
proved to be a successful approach for highly constrained problems such as
routing, scheduling, timetabling, etc. Parallelization of Ant Colony
Optimization reduces the execution time, increases the size of the problem,
etc.
