Blank empty wells that do not contain or have not seen any liquid at any point are one common form of blank controls, but more common are assay buffer blanks, i.e. wells filled only with the ELISA’s buffer/ diluent. Blanks are meant to analyze the contribution of background absorbance of the plastic and/or buffer to the signal. A blank is a control well that contains only the buffer but no sample or detector antibodies, used to measure background absorbance and allow for background subtraction from other data points, thereby ensuring a more accurate reading of the specific target analyte's signal.