First of all you must distinguish SFTP and secure FTP.
SFTP is SSH File Transfer Protocol, the name of the standard for file transfer, running (usually) on top of SSH.
There's also FTPS available, which is FTP-over-SSL.

Both SFTP and FTPS have their advantages and disadvantages. But both of them serve the matter of securing your data from being viewed or stolen by the intermediate nodes in the network (and don't think that this is rare - each router can log the data or filter it using some rules). Also they provide authentication of the peers in the communication, so you can be sure that you send your password to the host you needed, and not to the fake host (and DNS spoofing becomes more and more popular type of attack).

You can check the differences between SFTP and FTPS here.

Sincerely yours,
Eugene Mayevski

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