A tautomer is a type of isomer that exists in two or more forms, which can easily interconvert. This process typically involves the relocation of a hydrogen atom and a shift in the position of double bonds. Tautomerism is commonly observed in organic compounds, particularly in keto-enol tautomerism, where a ketone and an enol form can rapidly change into one another. Tautomers are important in various chemical reactions and biological processes. For example, the tautomeric forms of nucleotides can influence the stability of DNA and RNA structures. Understanding tautomerism is essential in fields like medicinal chemistry and biochemistry, as it can affect the behavior of drugs and biomolecules.