Identification

There are two methods to identify any item:
 * scroll of identify
 * spellbook of identify

There are several other tactics. Of them, the most important tactic is to identify wands. This is because you can identify many wands by engraving with them to the ground, and checking the results against wan1-343.txt. You will probably identify wands while your scrolls and rings are still unknown.

Here is a wand identification procedure:
 * 1) Engrave the name of the wand (for example, balsa), with your fingers.
 * 2) Engrave "Elbereth" with the wand on the same square.

If the balsa wand was a wand of teleport, then the word "balsa" will disappear. Actually, a wand of make invisible has the same effect. If the balsa wand was instead a wand of fire, you will identify the wand, and have Elbereth burned into the floor as a bonus. This is why so many NetHack players write Elbereth when testing their wands; it might be a wand of fire or wand of digging. However, you have to write something else on the square before you engrave with the wand; this is to avoid confusing a wand of make invisible with a wand of nothing.

Hopefully, with your wands identified, when that soldier ant appears and you need to flee to the staircase, but the fast ant will kill you first, then you can use a wand of slow monster or wand of sleep to slow the ant. All you know is that those bugs on the floor stopped moving, so maybe it is a wand of death. Be careful not to zap yourself by bouncing the bolt off a wall.

At Yet Another NetHack Site, they have The NetHack Object Identification Spoiler, written by David Damerell and converted to HTML by Kate Nepveu.