where Raman peak intensity being recorded on the SERS substrate (ISERS) from NSERS molecules that is related to the intensity measured from NRS molecules in Raman scattering configuration without the amplification. It is worth noting that determining the number of molecules being probed is often challenging and leads to uncertainties of determined EF values. There are numerous modifications of EF and the Analytical Enhancement Factor (AEF) represents one of the mostly used alternatives. AEF is defined similar to (1), but numbers of molecules N are replaced by the nominal concentrations of target analyte employed for each measurement. This definition is useful especially when there is no strong interaction between the analyte and the SERS-active element of the substrate or when using SERS-active liquids (colloidal suspensions). However, it often strongly depends on factors such as surface coverage and sample preparation procedures. We have found that among the manuscripts that reported any type of enhancement factor (around 25 % of the explored literature) 57% correspond to the EF definition and 43% to the AEF, with no evident link between enhancement factor calculation and substrate type.