S3 Buckets and Objects

Buckets and objects are the two fundamental building blocks of Amazon S3. Mastering their behaviour, naming conventions, metadata handling, and upload strategies is critical to designing effective storage solutions.

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Bucket Naming Rules

S3 bucket names are subject to strict rules because they form part of the URL used to access objects:

Rule	Detail
Globally unique	No two buckets across all AWS accounts can share a name
Length	3 to 63 characters
Characters	Lowercase letters, numbers, and hyphens only
Start/end	Must start and end with a letter or number
No IP format	Cannot resemble an IP address (e.g. 192.168.1.1)
No periods	Avoid periods — they break HTTPS virtual-hosted-style URLs

Good examples: my-app-assets, acme-corp-backups-2024, data-lake-raw

Bad examples: My_Bucket (uppercase and underscores), 192.168.5.4 (IP format), -start-with-hyphen

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Bucket Configuration

When you create a bucket, you can configure several important settings:

Region

Buckets are created in a specific AWS Region. Choosing the right region affects: