Electron Microscopy (EM) was developed in the early 1930’s as a tool that allowed its users to capture images of biological specimen with greater resolution than that in optical-based light microscopy. To achieve this increase resolution, EM utilizes a beam of electrons to survey a sample. This also allows for increased magnification. Utilizing the technical advantages of EM allowed for the advancement of many biological questions during the mid-20th century, including studies on the extra-cellular matrix, viral infection and the relationships between cell structure and function. EM continues to be a valuable tool for researchers, but the technical challenges of EM along with the advent of fluorophore genetics and confocal microscopy have perhaps minimized the usage of EM. This nanocourse will present a historical perspective on EM, including advantages and disadvantages of the technique, present the theory behind scanning and transmission EM, and discuss the development of new EM-based technologies.