Before revision:  Responding to this surge of interest, we review the existing literature in explainability URLanize it by (1) providing an overview of existing definitions,  (2) showing how explainability is implemented and how it exploits different modalities, and  (3) showing how the impact of explainability is measured.
After revision:  Responding to this surge of interest, we review the existing literature in explainability URLanize it by (1) providing an overview of existing definitions, by (2) showing how explainability is implemented and how it exploits different modalities, and (3) showing how the impact of explainability is measured.