Banners (decorative)

Banners are decorative furniture items that can be placed on the underside of blocks. Many are found naturally-placed in various biomes. There are also four crafted Banners (red, green, blue, and yellow). Banners can be hung off of blocks and off of platforms which are in their bottom position (after being struck three times with a hammer).

Faction Flags are Banners found in Dungeons. In post-Plantera worlds, the Faction Flags found hanging in a particular Dungeon area correspond to the background wall type (brick, slab, or tile), both of which signify the types of enemies that will spawn there. See Dungeon for more info.

There are currently a total of 23 decorative Banners: 4 crafted, 6 Faction Flags, 3 Floating Island, 6 Underworld, 3 Pyramid, 1 dropped from the Dark Mage during the Old One's Army event.

Faction Flags
These are Banners found placed in the Dungeon, in the same regions that are marked by different background walls. In their original locations, the banners hint at what Hardmode Dungeon enemies will spawn nearby.

Trivia

 * Each banner may be placed in a right- or left-facing orientation, but this is decided by which tile column in the world the banner is placed in. Placing it one block to the left or right will flip the orientation.
 * The four craftable banners correspond to the team colors in multiplayer, except for pink team that was introduced after the four banners.
 * The Gravity Banner seems to resemble the Gravitation Potion's buff icon.
 * The War Table Banner is the only one with 2x3 dimension instead of 1x3.
 * There is a pyramid flag of an Omega, which is actually a greek symbol, which was created millennia after Egypt fell.

History
装饰旗 Bannières (décorative) Знамя