Translocation mutations take place when a portion of a chromosome is relocated. The genes from one chromosome can move to another position on the same chromosome; alternatively, they can become incorporated into a different chromosome.
In some instances, known as reciprocal translocations, segments of two chromosomes are swapped with each other. When this happens, both chromosomes involved have essentially the same amount of genetic information before and after the mutation. Other times, genes are removed from one chromosome and inserted into another chromosome without any corresponding replacement. These instances are called unidirectional translocations and result in two chromosomes with noticeable differences in their post-mutation numbers of genes.
Translocations are not the only type of chromosome mutation. Other types of chromosome mutations include inversions, duplications and deficiencies.