Some information in complex problems may be acquired only through electron paramagnetic resonance (EPR) spectroscopy; examples include long-range (several nm) rigid body structural changes, protein conformational exchange on the μs order, conformational flexibility in intrinsically disordered regions of proteins, and protein structure, dynamics, and aggregation in highly heterogeneous systems. There are limited resources for first-year graduate students to learn the basis of EPR spectroscopy and receive guidance on using EPR in their research. The central purpose of this primer is to offer a concise combination of EPR basics with a broad collection of EPR applications in various research fields to bring graduate students up to speed on EPR spectroscopy. Graduate students should treat this primer as a quick overview of the background knowledge and typical literature of EPR so that their reading and self-learning can be more efficient. Different from the existing EPR review literature, this primer will focus on, from the views of first-year graduate students, what is needed to use EPR in their research, such as the general concepts in EPR, what information EPR can offer, and where to find more details about these aspects.