In this entry, we will discuss the most common magnetic measurement techniques that are used to characterize the magnetic properties of nanoscale magnetic materials. Advantages and disadvantages of each technique will be discussed. Studies of magnetic interactions and magnetization mechanisms at the nanoscale level are of interest not only from a fundamental perspective, but also from a technological perspective, because interactions can significantly affect magnetic properties, which, in turn, impacts their usefulness for technological applications. First-order-reversal-curves (FORCs) are an elegant, nondestructive tool for studying the magnetic properties of materials composed of fine (micron- or nanoscale) magnetic particles. We will also discuss the FORC measurement and analysis protocol and present results for various nanoscale magnetic materials.