Mathcore (also known as tech. metal, tech. hardcore, and math metal) is a style of metalcore recognized for a high level of technical musicianship. The subgenre has its roots in bands like Deadguy, Converge, Kiss It Goodbye, Training for Utopia, Botch, Turmoil, Coalesce, Bloodlet, Groundwork, Resurrection, Acme, Nerv, and Starkweather.
The music is usually filled with discordant, somewhat technical riffing, complex time signatures and song structures, and usually indecipherable lyrics. Songs played by bands of this style tend to vary from mere seconds in length to over 15 minutes and rarely feature a conventional verse-chorus song structure. Bands of the mathcore genre, combining so many influences, are often categorized differently depending upon the whims of journalists. Because metalcore is a hardcore punk/heavy metal crossover, bands such as Converge and The Dillinger Escape Plan are often referred to as "hardcore," and still others, such as As the Sun Sets and Daughters, are labelled as grindcore and noisecore, though only influenced by one or both genres. Other styles of music, such as blues-rock and free jazz, have been known to inspire various mathcore bands. Coalesce have been influenced by the former, to the extent of releasing a Led Zeppelin cover EP named There Is Nothing New Under the Sun, whereas The Dillinger Escape Plan are known to credit the latter. Other bands, such as Misery Signals, are, despite the presence of odd time signatures and heavy breakdowns, extremely melodic.