In this paper, a review of the literature related to the usability of e-learning (UEL) and the usability of adaptive e-learning (UAEL) is performed. This paper also identifies the most researched aspects, the tools and frameworks that have been developed and that take into consideration usability, as well as the factors and metrics. The methodology carried out in this research includes planning, development, and results. In addition, the descriptive analysis and the presentation of the articles are based on distribution of articles over time, distribution of articles between journals, and types of publications. The usability factors found in this review appear in a general context, but there is the need to adapt and propose new usability factors specific for a learning environment, in a tool aimed for students learn effectively. Therefore, it is necessary to investigate aspects of usability that can improve or enhance the learning experience in e-learning and adaptive e-learning.