A carriage return returns the carriage.

Seriously, a long time ago when type writers ruled the world and some computer were real dumb terminals, the ascii code told the hardware to physically reset the moving part that shifts the paper over back to home. The effect was the cursor returns the start of the line.
Note, it didn't move the line, just reset the machine to the beginning of it. To actually go to next line, you needed to issue a linefeed. If you issued a linefeed without a carriage return, the paper would go down a line, but not return to the beginning. It makes more sense if you've ever used a typewriter...
Windows does this correctly, using both a CR("\n" or ascii 13) and an LF("\r" or ascii 10) in it's files to indicate the start of a newline.
Unix, knowing it's not a teletype, chooses to do the same thing with one value, "\n". Mac also uses one value, but had to be different and uses the other half of the pair, "\r".
Many systems will translate "\n" as a newline for the OS they're currently on.
Hope that helps.