Ghosts I–IV

Ghosts I–IV is the sixth studio album by American industrial rock band Nine Inch Nails, released on March 2, 2008. The team behind the project included Nine Inch Nails front man Trent Reznor, studio-collaborators Atticus Ross and Alan Moulder, and instrumental contributions from Alessandro Cortini, Adrian Belew, and Brian Viglione. Reznor described the music of Ghosts as "a soundtrack for daydreams", a sentiment echoed by many critics who compared it with the work of Brian Eno and Robert Fripp. The songs are unnamed, and are identified only by their track listing and group number.

The album is the first independent release from Nine Inch Nails following its split from Interscope Records, and is an almost entirely instrumental album. Ghosts was initially intended to be a five-track EP, but the final release consists of four nine-track EPs, totaling 36 tracks. The album was released under a Creative Commons license (BY-NC-SA), and in a variety of differing packages and price points, including a US$300 "Ultra-Deluxe Limited Edition". Ghosts was initially released digitally on the official Nine Inch Nails website without any prior advertisement or promotion. Via the official Nine Inch Nails YouTube profile, a user-generated "film festival" was announced, where fans were invited to visually interpret the album's music and post their results.