Mutation:

However it may appear that the above recombinations are a little arbitrary that especially as points defining whether crossover and inversion occur are chosen randomly. Further it is important to notice that large parts of the string are kept, whether the string contained a region that scored well doing with the evaluation function that these operators have a good chance of passing such that region on to the offspring and especially where the regions are fairly small and  as in most GA problems, the overall string length is quite high. 

Furthermore the recombination process , it produces a large range of possible solutions. Moreover it is still possible for it to guide the search with a local rather than the global maxima with respect to the evaluation function. Hence for this reason, GAs regularly perform random mutations. Thus in this process, the offspring are taken and each bit in their bit string is flipped from a one to a zero or vice versa regarding to a given probability. In fact this probability is generally taken to be very small which say less than 0.01, so that only one in a hundred letters is flipped on average.