Writing IAM Policies: How to Grant Access to an Amazon S3 …

Doing so helps you control who can access your data stored in Amazon S3. You can grant either programmatic access or AWS Management Console access to Amazon S3 resources. For example, you might grant programmatic access to an application that gathers data from a website and then reads and writes the data to an Amazon S3 bucket.

https://aws.amazon.com/blogs/security/writing-iam-policies-how-to-grant-access-to-an-amazon-s3-bucket/