Mineral liberation is a key step in many mineral processing flow sheets and is achieved by breaking large pieces of ore into smaller particles which are suitable for the subsequent separation process. The ore being broken consists of mineral grains which may exhibit a range of properties affecting how they break. In the literature on mineral liberation the breakage of ore is frequently described as random or non-random, with several types of non-random breakage identified. With numerous researchers investigating this topic over the years, a variety of definitions of random and non-random breakage in mineral liberation have been presented in the literature. This paper examines the published work in this area and provides a comprehensive review of random and non-random breakage published in the literature on mineral liberation. It does not aim to revise the definition of these terms but to review the wide range of descriptors used by researchers in this field and identify common approaches to defining random breakage. The definition could be summarised as random liberation being the independence of breakage from both ore properties and mechanical properties during comminution. (C) 2016 Elsevier Ltd. All rights reserved.