Beta diversity is often assessed at different spatial and temporal scales and, consequently, has been defined in multiple ways. Here, we define four unique aspects of beta diversity that encompass the diverse applications of this concept in ecology and biodiversity management: 1) spatial beta diversity, 2) temporal variation in spatial beta diversity, 3) temporal beta diversity, and 4) spatial variation in temporal beta diversity. Each of these aspects can be analyzed using presence/absence or abundance data, and can be characterized using taxonomic, phylogenetic, or functional community features. The same approach can also be extended to measure change in abiotic environmental conditions and ecosystem services. The goal of our paper is to stimulate discussion and promote consistency in both the terminology and interpretation of beta diversity to improve understanding of scenarios of biotic and abiotic environmental change in space and time. Therefore, a unified terminology for beta diversity will facilitate enhanced communication not only among researchers but also between researchers and conservation practitioners.