Parallax

In the Settings menu from the main menu in Terraria, the Parallax option controls how much the background scrolls relative to the foreground.

Settings of 0-100 (inclusive) are available.
 * A setting of 0 (default) will have the background (which consists of sky, walls, etc) scroll with the foreground (what you walk on and bump into etc).
 * A setting of 100 will scroll the background tiles at a high speed compared to walking just a little to the left or right.

This effect is most noticeable Underground when you can see the dirt backgrounds scrolling when you move and have parallax set high.

History
Parallax 视差