An Item Box is the quintessential representation of the Mario Kart series: they are the unique, rotating boxes or panels which give players various types of Items to secure or take the lead. These item boxes always change in their appearances.
Item Boxes give an Item to any player who runs into them. The Item is randomly determined, but players who are generally in lower places will receive more useful Items, such as a Star or Bullet Bill, and players who are in higher places will get Items that do not help as much as those, such as a Green Shell or a Banana. Racers in middle places will receive Items that are in the middle, such as a Mega Mushroom or a Spiny Shell.
In Multiplayer Balloon Battle or Shine Runners for Mario Kart DS, once a player is eliminated, they can still drive around, and the get Item Boxes themselves as Items. They can be thrown out in front of the Kart and even dragged behind it, and they work exactly like regular Item Boxes.
In Super Mario Kart, item boxes didn't really exist- they were flat panels on the ground, and were called Question Blocks. If one is driven over, the item list would come up, and the items will quickly scroll vertically in a roulette-like fashion; the item it stops on is the item a player can use. Its essence stays throughout the whole series.
In Mario Kart 64, the boxes are orange and blue (and now they are 3D), and are sort of diamond shaped. It is impossible to tell from a distance if a Fake Item Box is really an item box, because a Fake Item Box looks exactly the same as an item box except for a barely noticeable upside-down question mark. There are still question marks in the middle, and the boxes rotate. They must be driven through rather than over.
In Mario Kart: Super Circuit, item boxes are box-shaped, 3-D, and cycle through a rainbow palette. They rotate horizontally and make roughly the same sound when they are hit as they do in Mario Kart 64.
In Mario Kart: Double Dash!!, the item boxes are a lot different, with an alternate design and are not as much of a diamond. They are now cubes with little squares all around them. The cubes do turn like they do in Mario Kart 64, but the question marks now have a part in the animation. The question marks bounce every time the cubes turn. Also, it is now easier to distinguish Fake Item Boxes from real ones due to their red color.
In Mario Kart DS, Item Boxes are practically the exact same as they are in Double Dash!!. They appear as rainbow squares on the touch screen. Fake ones are also the same and they're represented by a red square on the touch screen.
In Mario Kart Wii, the item boxes aren't too different, except that the square pattern was changed with a circle pattern on the cubes. The cubes are still animated the same as in Double Dash!!, and the Fake Item Boxes are still red with the same design as in Double Dash!!. However, this time the Fake Item Boxes twirl around.