sources: https://vutr.substack.com/p/amazon-s3-for-data-engineers?utm_source=publication-search For each object in a bucket, it has: key -> the unique key, which serves as its identifier prefix -> used for pretending in an organised folder structure used in partitioning objects for load balancing used in searching and returning objects with a same prefix version ID -> key for multiple versions of the same object value -> actual content stored, supporting any data in any format viewed as a sequence of bytes metadata system metadata -> assigned by S3 to manage the object user defined metadata -> assigned by users, e.g. tags