Hammers

Hammers are tools that are used to break background walls and to create half-blocks and slopes. Higher-level hammers (e.g. the Chlorophyte Warhammer) have high damage and can serve as weapons. Some can serve as both hammers and axes at the same time, known as hamaxes. New players do not spawn with a hammer, unless they are in in which case an Iron Hammer is provided for them.

Any hammer may be used to break Shadow Orbs and Crimson Hearts. A Pwnhammer or better is required to destroy altars, however, this is only possible in a world where the Wall of Flesh has been defeated. When attempting to destroy one with a lesser hammer, or prior to defeating the Wall of Flesh, the player will take damage equal to half their current health, and the altar will remain unharmed.

Despite not being a hammer, the Drill Containment Unit can destroy altars in Hardmode worlds and will slope surrounding blocks when mining.

There are currently different hammers available in Terraria,  of which are Hardmode-exclusive.

Trivia

 * All six Hardmode ores have no hammer or hamaxe available.

History
Hämmer Marteaux 망치 Młot 锤