S3: Object Storage

Definition: Amazon S3 (Simple Storage Service) stores files — called objects — in containers called buckets. It offers virtually unlimited, highly durable storage you access over the internet.

What S3 is great for

• Storing images, videos, backups, and documents
• Hosting static websites
• Holding data for analytics and machine learning
• Serving files to apps and users worldwide

Key ideas

• Buckets — top-level containers with globally unique names
• Objects — your files, each with a key (its name/path)
• Durability — S3 stores copies across multiple AZs; data is extremely safe
• Storage classes — cheaper tiers (like Glacier) for data you rarely access

A taste of the CLI

aws s3 ls
aws s3 cp report.pdf s3://my-bucket/reports/
aws s3 sync ./website s3://my-website-bucket

💡 Security note: new buckets are private by default — keep them that way unless you intentionally want public files.