Data IDs

A Mob/Item is missing from the list! What can I do?
This means that either the item/monster is saved in the Terraria client with its name, instead of ID, or it was added in a recent update and the page hasn't been updated yet. For example, items such as Gold Pickaxe and monsters such as Pinky and a few other colored slimes, are saved with their name, and can't be indexed with an ID.

What do I need these IDs for?
Basically, these IDs are used to index monsters, items, buffs, projectiles, prefixes and tiles in Terraria. They may be useful if you are developing clientside mods or texture packs or serverside mods like TShock (i.e. if you are working with the game's code). In Terraria's sprites some of these are labeled by ID so it makes finding those easier as well.