Emerging in the SoundCloud underground rap scene in the late 2010s, hexd is a musical approach and a form of electronic music characterized by heavily bit-crushed, sometimes sped-up and pitched-up vocals (particularly in the case of remixed material), and highly compressed and distorted production, typically made from existing material of genres such as trap, cloud rap, emo rap on one hand and trance, breakbeat and other electronic dance music styles on the other. With additional sound effects like delay and heavy reverberation, the genre aims to encapsulate a dreamy, murky, surreal atmosphere, sometimes used to create a sense of nostalgia, though many artists may instead focus on futuristic, near-mechanic ambiance. The genre is occasionally influenced by the hyper-real, mystical, and self-satirizing sound and aesthetic associated with vaporwave and other genres in the bigger vapor movement, with certain producers borrowing elements of the sample manipulation and processing typical of these genres.

Originally developed by the Hexcastcrew group, hexd began attracting attention with the group's member cargoboym's Rare RCB hexD.mp3 mix, made from existing Reptilian Club Boyz tracks, whose sample-rich music and unique aesthetic would remain influential for hexd in the following years. The genre would grow exponentially during the next two years, spawning many similar DJ mixes generally based on hip hop material, but also on a variety of EDM genres. The distinct DJing style that emerged further incorporated nightcore, Florida fast music, and chopped and screwed, with producers incorporating the aforementioned editing techniques by speeding up, cutting, and compressing existing tracks into a "hexd" wall of sound.

The main derivative that developed from hexd came to be known as "crushed trap", a term popularized by 999 Heartake Sabileye who used it for their many mixes of the genre, remixing and heavily bit-crushing existing trap songs into a hazy pool of "hexd" ambiance. A competing term (or, in some interpretations - an affiliated style) for the derivative form of psychedelic, sped-up, and glitchy trap music is "surge", coined by Kittenpuke and popularized by Dismiss Yourself - whose label Dismiss Yourself and YouTube channel would become a central hub for the genre. Many of hexd's prominent artists were also featured in Dismiss Yourself's Surge Compilation Vol. 1.

With many of its listeners and producers affiliated with the Rate Your Music community, the genre became an influence on other styles of internet rap and electronic music, like the SpaceGhostPurrp and BMB Deathrow-affiliated dark trap genre, certain styles of SoundCloud-based cloud rap and pop rap like the late 2010s-born glitchcore trend, and even wave and bubblegum bass. Another prominent derivative of the sound includes a form of hexd/crushed trance mixes, led by producers such as Sienna Sleep, Visavril, and iANO. A prominent visual style of artists of the genre is commonly characterized by a distinct low-quality, DIY, "deep-internet" aesthetic that seeks to provoke video game/2000s nostalgia, and pictures/visual elements are commonly taken (and edited) directly from Anime series.