The semantic web for Earth and environmental terminology (SWEET) is an investigation in improving discovery and use of Earth science data, through software understanding of the semantics of web resources. SWEET is a collection of ontologies conceptualizing a knowledge space for Earth system science, represented using the web ontology language (OWL). It includes both orthogonal concepts (space, time, Earth realms, physical quantities, etc.) and integrative science knowledge concepts (phenomena, events, etc.). The ontology is modularized into 224 component files in this version, each representing a different namespace, with numerous dependencies implemented by OWL imports between the namespace. Component factoring may change in future versions. The original version was developed by Robert Raskin at JPL (see Raskin and Pan, 2005: https://www.sciencedirect.com/science/article/pii/S0098300405001020 ). Stewardship has been taken over by the Earth Science Information Partners Federation (ESIPFed), managed through a GitHub repository at https://github.com/ESIPFed/sweet. See https://github.com/ESIPFed/sweet/blob/master/CONTRIBUTING.md for information about providing comments or contributing to development of SWEET.