This educational lecture will give a broad overview of Quantitative Susceptibility Mapping. After explaining what magnetic susceptibility is and how we can measure it, I cover the data acquisition aspects, coil combination, unwrapping, masking, background field correction and dipole inversion. Then I show different toolboxes that enable QSM processing. I discuss the topic of referencing QSM results in for example group studies and conclude with a bigger picture and wish list of features that I would like to see in the QSM method development going forward.