Binary mode

From HostPedia

Transfering Files with FTP software to a host can be done in two modes, Binary Mode and ASCII Mode. Binary Mode is usually used to transfer non-text files while ASCII Mode is used for text-files.

If text files are sent in Binary Mode to another computer - the transfered file will be corrupted, ASCII and other text formats don't encode the "end of line" info the same way as non-text files. Using ASCII Mode for .exe, .zip, .rar files (and other non-text files) would also result with a corrupted file.

While most FTP clients has an auto-detect feature that can switch the modes based on the file's extension, usually it is also optional to set it manually for each file separately.

Most FTP client applications has the option to send files in both modes. In text mode, the data gets translated properly so it arrives in a readable format.