In a nutshell
S3 is the Simple Storage Service that lets you store and retrieve data on the AWS cloud. You create S3 “buckets” to store your data in. Think of a bucket like a hard drive on the cloud.
You can create as many buckets as you like and use them to store different types of data (e.g., a bucket for user images, a bucket for generated reports, a bucket for database backups).
You can assign policies to each bucket to control what entities can access them (e.g., authenticated users, anyone, or a particular service) and what they can do (e.g., read or write).