As double-stranded DNA is heated a temperature is reached at that the two reaction strands divided. This procedure is called as denaturation. The temperature at that half of the DNA molecules have denatured is called as the melting temperature or Tm for that DNA if the temperature is now lowered and falls below the Tm, the two corresponding strands will form hydrogen bonds with each other once more to reform a double-stranded molecule. This procedure is called as renaturation (or reannealing). In reality, double-stranded structures can form between any two single-stranded nucleic acid molecules (DNA-RNA, DNA-DNA, RNA-RNA) provided in which they have sufficient complementary nucleotide series to make the double-stranded molecule stable under the conditions used. The general name given to these procedures is hybridization and the double-stranded nucleic acid product is called as a hybrid.