Nature is of course a great and immense source of inspiration for solving hard and complex problems in computer science since it exhibits extremely diverse, dynamic, robust, complex and fascinating phenomenon. It always finds the optimal solution to solve its problem maintaining perfect balance among its components. This is the thrust behind bio inspired computing. Nature inspired algorithms are meta heuristics that mimics the nature for solving optimization problems opening a new era in computation .For the past decades ,numerous research efforts has been concentrated in this particular area. Still being young and the results being very amazing, broadens the scope and viability of Bio Inspired Algorithms (BIAs) exploring new areas of application and more opportunities in computing. This paper presents a broad overview of biologically inspired optimization algorithms, grouped by the biological field that inspired each and the areas where these algorithms have been most successfully applied.