Opening Scenario
Your backend needs to store user-uploaded photos, serve static frontend assets, archive nightly database exports, and hold Lambda deployment packages. These files range from 1 KB to 5 GB. Some are read thousands of times per second; others are written once and never touched again. You need storage that scales without you thinking about it, costs almost nothing for cold data, and can be accessed from anywhere in AWS. What do you use?
Question Progression
Concept 1: What kind of storage is S3 and how does it differ from a filesystem?
Question You're used to filesystems with directories and file paths. How is S3 different, and why does that matter?
Reasoning
S3 uses an object storage model, not a block or file storage model. There are no real directories — only a flat namespace of objects inside a bucket. What looks like a path (photos/2024/user-123/avatar.jpg)…
In the full tutorial
- When to Reach for S3
- Interview Follow-Ups