Amazon S3 is an object storage service that is designed to store and retrieve any amount of data from anywhere on the web. It does not require a pre-defined schema and is not suited for traditional relational database operations that depend on a structured schema. Instead, it allows for storing data as objects within resources called buckets, with a flat namespace. This question is designed to test the candidate's knowledge of the characteristics of Amazon S3 compared to other storage services that may support structured data and predefined schemas.