The backslash is there to "escape" the space that follows it. Usually a space is used to separate command-line arguments, like if you were copying "somefile" from, say, "Program Files" to "abc":
cp Program Files/somefile abc
The space would be interpreted incorrectly, thinking that you wanted to copy the file from "Program" to "Files/somefile". Anyhow, the backslash is used to tell bash, or other shells, that the space is part of the filename. The backslash is used for a lot of other things too. It basically means "the character that comes next should be treated literally," or sometimes "treat the next character in some special way." It's also used in some programming languages like C, for characters that you can't type in ASCII (such as \n for newline, \t for tab, etc.)
Last edited by wapcaplet; 12-20-2003 at 02:41 PM.