Neil Young is a Canadian-American musician, singer, and songwriter that became popular in the late 1960s. He is most known as the guitarist for Buffalo Springfield, being a part-time member of Crosby, Stills, Nash & Young, and for his solo career. Since the beginning of his solo act, with his backing band Crazy Horse, he has released many hit albums. Themes of environmental spirituality and activism became more prominent in his work throughout the 1990s and 2000s. He became more outspoken about the environment as time went on and has referred to issues surrounding the proposed use of oil pipelines as "scabs on our lives".