The prompt is usually specified in AUTOEXEC.BAT and the standard prompt "c:\>" is :

prompt $p$g

Command Effect $t current time $d current date $p current path $n current driveletter $v current version $e escape character $h backspace character $_ newline character

Command Effect $g > $l < $q = $$ $ $b | $a & $c ( $f )

With these characters one can create an individual prompt:

prompt time is: $t$_date is: $d$_path is: $p$g

If one loads ANSI.SYS in the CONFIG.SYS then the prompt is also capable of changing colors by using escape sequences "$e[" (Here Bright Red and Green).

prompt $e[1;31;40m$p$g$e[1;32;40m

More Info MS KB83064
More Info MS KB135484 (Escape Sequences & Color Codes etc.)