It is now well-known that ground motion characteristics can be influenced significantly by local site characteristics. In general, soil characteristics were classified by considering the time-average velocity down to 30 m (Vs30). However, recent studies have showed that the fundamental site period is a better proxy than Vs30, or the most complementary parameter to Vs30, for this purpose. Recent earthquakes have also revealed that the largest amplifications occur at the fundamental site period and cause heavy damage or the collapse of structures when they have similar vibrational characteristics with the site’s fundamental period, i.e., resonance. Therefore, many studies in the literature have been performed to determine the fundamental periods of layered soil profiles using different analytical, approximate, and data-driven methods. However, there is a requirement to evaluate these methods by following a systematic procedure. Hence, the reader will receive a comprehensive review of the available procedures for determining the site’s fundamental period of layered soil profiles and their applications at different scales, along with an exploration of current research gaps.