The two most common data types in usage are ASCII and binary.
ASCII is the default data type, and is intended for the transfer of text files. A line of text is followed by
Binary type (known as IMAGE in FTP) is used to transfer binary files. A byte-by-byte copy is made of the source file. Graphical images, video and executable files are all binary files. If they are transferred as ASCII, they will be corrupted.
Next: Session Commands