In this chapter, we present a perspective on a category of grant-free communication methods, specifically those based on random access. They are well-suited for scenarios involving a large number of devices transmitting sporadically with short messages, commonly encountered in Internet-of-Things (IoT) communication scenarios. These methods, often referred to as modern random access, have recently emerged and generated significant interest. We discuss, in an introductory and tutorial manner, the basic methods for evaluating these communications as introduced in the literature. Additionally, we provide insights into their performance.