As part of an invitation by Nature Reviews Methods Primers we have published together with Ken Ataka and Joachim Heberle a review on the method of ‘Surface-enhanced Infrared Absorption Spectroscopy’, SEIRAS. SEIRAS enhanced IR spectra at interface by 102 – 107 and, thus, allows to study single-layered assemblies. We discuss the basics, important experimental consideration as well as highlight case studies from electrochemistry, trace analysis, and biofunctional studies.