Complex sentence: Metallica is an American heavy metal band from Los Angeles, California, whose releases include fast tempos, instrumentals, and aggressive musicianship that placed them as one of the founding "big four" of thrash metal alongside Slayer, Megadeth, and Anthrax.
Split into simpler sentences: Metallica is an American heavy metal band from Los Angeles, California. The band's fast tempos, instrumentals, and aggressive musicianship placed them as one of the founding "big four" of thrash metal alongside Slayer, Megadeth, and Anthrax.