The method of photometry is different in a microplate reader versus a standard spectrophotometer. The absorbance of a solution in a cuvette is determined by sending light through the sample horizontally in the cuvette whereas in a microplate well, the light is sent through the sample vertically. Microplate spectrophotometers, also called microplate readers, allow researchers to analyze multiple samples in parallel using 6- to 1536-well formats, as opposed to single sample measurements. Instrument design, user interface capabilities, and cost play key roles in purchasing a suitable microplate reader. Spectrophotometer detection parameters are principally UV (ultraviolet), UV/Vis (ultraviolet/visible), or fluorescence absorbencies. Luminescence is often used to read ELISA samples, but enzyme kinetic studies and cell signaling assays commonly require fluorescence scanning, so choosing a reader depends on the multiplicity of research requirements. Multimode selections, single filter change-out options, incubator inclusion, sample mixing/shaking, and read time are imperative considerations to assess when selecting a microplate spectrophotometer. Some microplate readers deliver an interactive user interface to include data acquisition, but others supply the only instruments and read set-up options, which may require the purchase of accessory equipment.