The advent of super-resolution techniques has fundamentally changed how biology is done and what biological questions it is possible to ask and answer now that we can image beyond the resolution limit. There are a number of super-resolution techniques, each with their own strengths and preferred use cases. Structured illumination microscopy (SIM) relies on spatially structured illumination light to encode super-resolution information in a resolution limited image. A number of these resolution limited images are used together to extract the super-resolution information, producing a reconstructed image with twice the resolution of the original images. The number of images required to obtain a super-resolution image is considerably less than most other super-resolution techniques, making SIM ideally suited to imaging dynamic biological processes. Herein we will cover how to think of images as information in Fourier space (including an introduction to Fourier mathematics sufficient to understand this), the mathematics behind SIM and how images are reconstructed, and the strengths and limitations of SIM.