CarriageReturn-LineFeed = Return

As with many thing computational, it depends on the OS (operating system). In plain text files on DOS/Windows, the special character representing the end of a written line of text is a simple CR (carriage return ASCII value 13 in decimal, 0x0D in hex, CR, or ctrl-M), on Un*x it's a simple linefeed or newline character (ASCII value 10, 0x0A, LF, or ctrl-J). On the Mac under pre-MacOsX days it was CR-LF, and now it can be that or a simple Un*x LF.

The first 32 non-printable characters in the ASCII chart are control characters like ctrl-G (bell, BEL), ctrl-I (horizontal tab, HT), and other teletype controlling codes. The last 5 of the first 32 aren't mapped to control sequences, but include the value for the escape (ESC) key.

See http://en.wikipedia.org/wiki/Ascii for more info.