https://docs.aws.amazon.com/AmazonS3/latest/userguide/object...

Arbitrary name+value pairs attached to S3 objects and buckets, and readily available via the S3 API. Metadata, basically. AWS has some tie-ins with permissions and other features, but tags can be used for any purpose. You might encode video multiple times at different bitrates, and store the rate in a tag on each object, for example. Tags are an affordance used by many applications for countless purposes.

Thanks! I understand what tags are, but not what an "object" was in this context. Your example of multiple encodings of the same video seems very good.