There are many things that can be put in the dos prompt
area, the common
was the default
The dos command
prompt $d $t $p$g
would return a prompt that resembled
Fri 08-04-2000 21:03:59.58 C:\WINDOWS>
with the date, time, current path and the greater than symbol.
There are many more parameters, but they are mostly useless.
Simply intputting a string after the command returns the string as the new prompt.