**S3**, or Amazon Simple Storage Service, is an object storage service provided by [[AWS]], that organizes arbitrary objects in buckets. A S3 **bucket** is an object container that is identified with a unique name for an account. You can create up to 100 buckets per account and they are bound to a specific region. S3 **objects** are format-agnostic objects to be stored in a bucket. They can be up to 5 TB and contain a set of metadata. That metadata can be of two kinds: - System metadata, which includes creation timestamp, size, MD5 digest, content-type... - User metadata, which are optional data set by the user at creation time. Those objects are identified by its **key** (or key-path), which could be understood as a file name. S3 does not have a hierarchical system or folder system, but using slashes to mimic it works just fine since object fetching works on a prefix-base.