In their natural state, most of the cells and microorganisms that we observe under the microscope lack color and contrast. This makes it difficult, if not impossible, to detect important cellular stru...In their natural state, most of the cells and microorganisms that we observe under the microscope lack color and contrast. This makes it difficult, if not impossible, to detect important cellular structures and their distinguishing characteristics without artificially treating specimens. Here, we will focus on the most clinically relevant techniques developed to identify specific microbes, cellular structures, DNA sequences, or indicators of infection in tissue samples, under the microscope.