Bars

Bars are crafting materials generally crafted from mined ores at a Furnace. Crafting most ore-related items requires that raw ores are first crafted into bars.

There are currently 23 different bar types. Obtaining most of these only requires their respective ores as crafting ingredients. Hellstone, Spectre, and Shroomite Bars are exceptions that require a secondary material in addition. Hallowed Bars are not crafted but are instead dropped by the mechanical bosses. Some bars may also be obtained randomly from crates.

Trivia

 * Hallowed Bars are the only bars to not require an ore to be made.
 * Although a single bar is consumed when it is placed, the tile sprite appears to be 3 or possible 4 bars stacked on top of each other.
 * The old bar textures are actually modified versions of the old  ingot textures. (For Example: See the old Minecraft iron ingot then the old Terraria iron bar.)