Genetic recombination is the production of new combinations of alleles, encoding a novel set of genetic information, e.g., by the pairing of homologous chromosomes in meiosis, or by the breaking and rejoining of DNA strands, which forms new molecules of DNA. This last type of recombination can occur between similar molecules of DNA, as in the homologous recombination of chromosomal crossover, or dissimilar molecules, as in non-homologous end joining. V(D)J recombination in organisms with an adaptive immune system is a type of genetic recombination that helps immune cells rapidly diversify to recognize and adapt to new pathogens. Recombination is a common method of DNA repair in both bacteria and eukaryotes.