Leonard Bernstein Bernstein was influenced by his friend Aaron Copland. Leonard Bernstein's West Side Story Leonard Bernstein was a composer who was able to write music in many different styles, including classical, pop and jazz. In many of his works you can hear all these styles combined into one piece. Think about some of the music you listen to today.
Many songs borrow from different styles of music.
For example, a country western song might have some blues influence. When something has an effect on something else that is considered an influence.