Scanning electron microscopy (SEM) is a technique used to capture a picture of a sample by focusing a beam of electrons onto the sample, scanning the beam around the surface of the sample, and then detecting the electrons after they have been scattered off of the sample. The scattered electrons are then analyzed to produce an image of the sample. In general, imaging methods that make use of electrons can offer higher resolution than those based on light due to the shorter wavelengths associated with electrons (as opposed to photons). SEM can be used to obtain very high-resolution images of a sample on length scales as short as one nanometer. The downside to electron-based methods (again, as opposed to using light) is that the electron-based methods are often damaging to the sample (especially to live samples), whereas shining a beam of light on a sample doesn’t typically cause a lot of damage. SEM has been useful for characterizing materials as well as a wide range of other kinds of samples.