Multipart upload
Also called: Resumable upload, Chunked upload
Uploading a large file as separately sent parts that storage combines at the end, so failures only retry one part.
Definition
The client starts an upload, sends numbered parts (each with its own presigned URL, possibly in parallel), can ask which parts storage already has to resume after a failure, and finally completes the upload so the parts are assembled into one object. Incomplete uploads keep their parts and are billed until they are aborted, so buckets need a lifecycle rule to clean them up.
In practice
A 400 MB video is sent as 50 parts of 8 MB; after a tunnel, the app resumes from part 37.