Spacer DNA, also known as non-coding DNA, is a section of DNA that is not involved in coding for proteins. It is often referred to as junk DNA because it does not seem to have any specific function. However, recent research has revealed that some spacer DNA can regulate gene expression and play a role in epigenetic modifications. Synonyms for spacer DNA include non-coding DNA, intergenic DNA, non-coding region, and non-coding sequence. These terms refer to the same section of DNA that does not carry genetic information for protein production. Although it was once thought to be inconsequential, spacer DNA is now recognized as playing an important role in the regulation of gene expression.