Object Storage Fundamentals
When you need to store files in the cloud — user uploads, images, backups, or static assets — you'll likely use object storage. It's become the default choice for file storage in modern applications, and understanding how it works will help you make better architectural decisions.
What Is Object Storage?
Object storage is a flat storage system designed for files. Unlike your computer's filesystem with nested folders, or a database with structured tables, object storage treats each file as an independent "object" with three components: the file data itself, metadata describing the file, and a unique identifier (key).
Objects live in buckets — containers that group related objects together. While most interfaces show what looks like folders, they're actually just prefixes in the object key. The path images/users/photo.jpg isn't a folder structure; it's a single key that happens to contain slashes.
You access objects through HTTP APIs rather than mounting drives. This makes object storage incredibly scalable — you can store petabytes without worrying about disk management.
When to Use Object Storage
Object storage excels at specific use cases. User uploads like profile pictures, documents, and videos fit perfectly. Static assets for websites — CSS, JavaScript, and images — work well because they can be served directly or through a CDN.
Backups and archives benefit from object storage's durability and low cost. Most providers guarantee 99.999999999% durability (eleven nines), meaning your data is incredibly safe. Data lakes for analytics also use object storage because it handles massive datasets affordably.
However, object storage isn't ideal for everything. If you need to modify files frequently, search within file contents, or require filesystem semantics, consider other options.
Major Providers Compared
AWS S3 pioneered object storage and remains the most feature-rich option. Its API became the industry standard — many other services are "S3-compatible."
Google Cloud Storage integrates tightly with GCP services. Azure Blob Storage fits naturally into Microsoft ecosystems.
For cost-conscious projects, Cloudflare R2 offers S3 compatibility with zero egress fees — a significant savings for high-traffic applications. DigitalOcean Spaces provides simplicity at lower prices. Backblaze B2 offers the cheapest storage rates, ideal for backups and archives.