File transfer

The source can keep its copy. The job is done when the destination has a usable file, not when a progress bar first moves.

People use the phrase for three different jobs. A person sends a cut to a client. A script pushes a nightly export to a partner. A browser pulls an installer from a vendor. The bytes move in each case. The control plane does not. A link in an email, an FTP session, and a managed job with a retry schedule are not the same operation wearing different labels.

The move has a direction, a size, a channel, and a completion test. Direction is file upload or file download. Size decides whether email, a browser form, or a dedicated path is even eligible; see large file transfer. Channel is the protocol: FTP, SFTP, or HTTP as defined in RFC 9110. Completion is not "the socket closed." Operators check byte count, a checksum, or an application-level receipt. RFC 959 treats the file copy itself as the point of the protocol, separate from the terminal session that happens to carry the commands.

A studio finishes a 4.2 GB master on Monday at 16:10. Email rejects it. The producer uploads it to object storage and sends an expiring link. The client's browser downloads 4.2 GB and the player opens the file. That sequence is one file transfer with an upload leg and a download leg. If the client receives 4.0 GB and the player errors, the transfer failed even though a link was sent.

File sharing is the neighbor people swap in. Sharing often means ongoing access to a folder that still lives in the sender's account. Transfer means a copy landed somewhere else. A shared drive permission does not, by itself, prove a copy left the building. Managed file transfer is the other neighbor: a product category that adds scheduling, audit, and retry on top of a protocol. The protocol can run without that product. The product is pointless without a protocol underneath.

Common miss: calling any attachment an online file transfer. A 2 MB PDF in email is a transfer. So is a 40 GB camera roll. The interesting differences are the size ceiling, whether the sender's server keeps the object, and whether anyone can show an audit row for the move.