Technical death metal (also referred to as tech-death) is a musical subgenre of death metal that began and developed in the early- to mid-1990s, with particular focus on challenging, demanding instrumental skill and complex songwriting.
Some of the distinct features of this genre include dynamic song structures, complex and atypical rhythmic structures, abundant use of diminished chords and arpeggios, frequent employment of odd time chord progressions, and constant use of string skipping on the guitars. Bass lines are usually complex and the drums are extremely fast-paced with abundant use of blast-beats and other extreme drumming techniques.
One of the key works that cemented the subgenre was Atheist's debut album Piece of Time, released in 1990, which took death metal into a more intricate level while incorporating influences ranging from jazz fusion to progressive metal. In 1991, New York death metal group Suffocation released their debut album Effigy of the Forgotten, which focused on pairing speed and brutality with a "sophisticated" sense of songwriting. Atheist's second album Unquestionable Presence, Pestilence's third album Testimony of the Ancients, and Death's fourth album Human were all released that very same year, defining the path for death metal's newly found intricateness and having proved to be especially influential on later 1990s and 2000s technical death metal bands.