AWS long-term archival storage service for data you rarely access. Like putting old documents in a warehouse - cheaper to store but takes time to retrieve.
A company stores old employee records in Glacier for compliance, accessing them only when legally required.
All are low-cost object storage options designed for long-term retention with higher retrieval latency and/or retrieval fees. AWS implements Glacier as S3 storage classes; Azure uses Blob access tiers; GCP uses storage classes; OCI uses storage tiers. Retrieval time and minimum storage duration vary by provider and tier.