We present a brief review of Genetic Algorithms (GAs) that do not require the manual tuning of their parameters, and are thus called Parameterless Genetic Algorithms (pGAs). There are three main categories of Parameterless GAs: Deterministic, Adaptive and Self-Adaptive pGAs. We also describe a new parameterless Genetic Algorithm (nGA), one that is easy to understand and implement, and which performs very well on a set of five standard test functions.