Ghosts appear in Mario Kart's Time Trial mode. These Ghosts are replays of previous Time Trial attempts. The player can race against these Ghosts on the track that the ghost was saved on. In Mario Kart 64, Ghosts were saved on Controller Paks. As such, Ghosts cannot be saved in the Virtual Console version of the game. In most games, you can save one Ghost per track, unless you take a very long time to complete the three laps of the course. In cases in which ghost data can't be stored, an icon will come up beneath TIME. In Mario Kart DS and Mario Kart: Super Circuit, you can download friend's Ghosts wirelessly or through a Game Boy Advance connector, for two Ghosts per track. In Mario Kart Wii, you can download Ghosts from the Nintendo Wi-Fi Connection, including Rival Ghost, Champion Ghosts, and Friend Ghosts.
In the more recent Mario Karts, if the player can get a fast enough time, they'll unlock a Ghost made by one of the developers who made the game. These times are very tough as they use the best tricks for their track. In Mario Kart 64, Staff Ghosts were referred to as Course Ghosts. The game only had three course ghosts, appearing in Luigi Raceway, Mario Raceway, and Royal Raceway, respectively. Mario Kart DS improved upon this by including one unlockable Ghost per track, which are the equivalent to Mario Kart Wii's Expert Staff Ghost. In Mario Kart Wii, there are two developer Ghosts per track: one called "Staff Ghost" the other called "Expert Staff Ghost". The normal ghost can be easily beaten with practice on the track. The expert Ghost uses every trick in the book; Mushrooms placed perfectly, stunts everywhere, and drifting right at the edge of the track. In Mario Kart 8, only normal Ghosts appear, however.