"Trains" is a pivotal track from Porcupine Tree's 2002 album In Absentia, marking a significant shift in the band's sound. Released during a period of intense experimentation, the song blends progressive rock structures with atmospheric electronic elements, reflecting the group's evolving identity. The recording features layered vocals and complex instrumentation that define the album's introspective mood. As a cornerstone of their discography, the track exemplifies the band's ability to merge technical proficiency with emotional depth, influencing the progressive metal and post-rock scenes of the early 2000s. Its enduring presence in their catalog highlights its role in establishing Porcupine Tree's reputation as innovators within the genre.