This is a useful thread, particularly because this question gets asked from time to time by new members. I even search for this thread on some occasions as a reference. So, I propose that we sticky this thread for easy access
Second, I just realized that Rogue's symbols have been totally unmentioned here! Well, here they are, ripped verbatim directly from the original manual:
@ This symbol represents you, the adventurer.
-| These symbols represent the walls of rooms.
+ A door to/from a room.
. The floor of a room.
# The floor of a passage between rooms.
* A pile or pot of gold.
) A weapon of some sort.
] A piece of armor.
! A flask containing a magic potion.
? A piece of paper, usually a magic scroll.
= A ring with magic properties
/ A magical staff or wand
ˆ A trap, watch out for these.
% A staircase to other levels
: A piece of food.
A-Z The uppercase letters represent the various inhabitants
of the Dungeons of Doom. Watch out, they can be nasty
and vicious.