Women in music describes the role of women as composers, songwriters, instrumental performers, singers, conductors, music scholars, music educators, music critics/music journalists and other musical professions. As well, it describes music movements (e.g., women's music, which is music written and performed by women for women), events and genres related to women, women's issues and feminism. In the 2010s, while women comprise a significant proportion of popular music and classical music singers, and a significant proportion of songwriters (many of them being singer-songwriters), there are few women record producers, rock critics and rock instrumentalists. Notable women artists in pop, such as Bjork and Lady Gaga have commented about sexism and gender discrimination in the music industry. In classical music, although there have been a huge number of women composers from the Medieval period to the present day, women composers are significantly underrepresented in the commonly performed classical music repertoire, music history textbooks and music encyclopedias; for example, in the Concise Oxford History of Music, Clara Schumann is one of the only female composers who is mentioned.