DNA-DNA hybridization refers to the process of joining two strands of DNA together to form a hybrid strand. It is an important technique used in molecular biology and genetics to determine the level of relatedness between different species or strains. Synonyms for this term include DNA reassociation, DNA-DNA annealing and DNA melting. Other techniques used in conjunction with DNA-DNA hybridization include DNA sequencing, PCR amplification, and gene expression analysis. Understanding DNA-DNA hybridization plays a vital role in our understanding of biodiversity, evolution, and genetics, helping researchers to uncover the complex relationships between different organisms and species.