Why S3 matters
Amazon S3 is the object storage service that powers a huge part of the internet. If you build anything that stores files, serves static assets, or handles uploads, you'll likely touch S3. It's simple in theory: buckets hold objects (files), and each object has a key (path). But the details matter, especially around permissions, consistency, and cost.
Buckets and keys
A bucket is a global namespace. Bucket names must be unique across all AWS accounts, so you can't just name yours uploads. Use a prefix like mycompany-uploads. Keys are just strings; they can contain slashes to mimic folders, but S3 doesn't really have folders. That's why listing objects with a prefix is the way to "browse" a directory.
aws s3 ls s3://mycompany-uploads/images/
