binary file

storage, operating system A file containing binary data,

i.e. arbitrary bytes or words, as opposed to a text file

containing only printable characters (e.g. ASCII characters

with codes 10, 13, and 32-126).

On modern operating systems a text file is simply a binary

file that happens to contain only printable characters, but

some older systems distinguish the two file types, requiring

programs to handle them differently.

A common class of binary files is programs in machinelanguage ("executable files") ready to load into memory and

execute. Binary files may also be used to store data output

by a program, and intended to be read by that or another

program but not by humans. Binary files are more efficient

for this purpose because the data (e.g. numerical data) does

not need to be converted between the binary form used by the

CPU and a printable (ASCII) representation. The

disadvantage is that it is usually necessary to write special

purpose programs to manipulate such files since most general

purpose utilities operate on text files. There is also a

problem sharing binary numerical data between processors with

different endianness.

Some communications protocols handle only text files,

e.g. most electronic mail systems before MIME became

widespread in about 1995. The FTP utility must be put into

"binary" mode in order to copy a binary file since in its

default "ascii" mode translates between the different text

line terminator characters used on the sending and receiving

computers.

Confusingly, some files produced by wordprocessors, and

rich text files, are actually binary files because they

contain non-printable characters and require special programs

to view, edit, and print them.

(2002-01-19)