Two Key Concepts to Understand First

Durability

Availability


Storage Classes — Quick Reference

Storage Class Availability Min. Billing Best For
S3 Standard 99.99% None Frequently accessed data
S3 Standard-IA 99.9% None Infrequent but rapid access
S3 One Zone-IA 99.5% None Recreatable infrequent data
S3 Glacier Instant 90 days Quarterly access, ms retrieval
S3 Glacier Flexible 90 days Archives, hours retrieval
S3 Glacier Deep Archive 180 days Long-term cold storage
S3 Intelligent-Tiering None Unknown or changing access patterns
S3 Express One Zone 99.95% None Ultra-low latency workloads

You can move objects between classes manually or using S3 Lifecycle Policies (automated rules).


1. S3 Standard — General Purpose

Use Cases: Big Data analytics, mobile and gaming applications, content distribution