Gustav Mahler was a renowned Austrian composer and conductor who lived from 1860 to 1911. He is best known for his symphonies, which are considered some of the most important works of the late Romantic period. He also wrote several choral works, including his Symphony No. 8, which is often referred to as the 'Symphony of a Thousand'. Mahler's music is characterized by its emotional intensity and its use of traditional forms such as sonata form and variation form. His influence on 20th century music is undeniable, and he is considered one of the most important composers of the late 19th and early 20th centuries.