Low-cost storage for data that's rarely accessed but must be kept long-term. Like a storage unit in the basement - cheap to keep things, but takes time to retrieve them.
Hospitals use archive storage for old patient records that must be kept for legal reasons but are rarely accessed.
All are low-cost object storage options designed for long-term retention with higher retrieval latency and/or retrieval fees. AWS offers distinct Glacier classes; Azure uses an Archive tier within Blob Storage; GCP uses an Archive storage class; OCI provides an Archive tier. They differ mainly in minimum storage duration, retrieval time options, and pricing for retrieval and early deletion.