Abstract
Software reliability represents a topic of paramount importance in many sectors of industry and society. In addition to this, it is characterized by a high-degree of dynamism as shown in literature. Published papers have addressed this research from different points of view, leading to considerable efforts to get a complete overview of existing solutions. This paper focuses on metrics in software reliability in order to: investigate the state-of-the-art in the field of software reliability, synthesize available evidence of their usage, and identify the most popular ones. We have carried out a Systematic Mapping Study that structures and analyzes the literature on software reliability metrics, obtaining a total of 386 studies. On the basis of 128 selected primary papers, the results show an increasing diversity of work. They represent a valid starting point for selecting the most useful metrics for an assessment of reliability in a software system.