Describe the concept of "program music".

The concept of program music refers to instrumental music that is intended to evoke a narrative, tell a story, or convey an image or scene without the use of lyrics. This genre of music often uses thematic elements and motifs to illustrate specific ideas, emotions, or visual representations, making it distinct from other forms of music that may not have such descriptive intentions.

Program music can take various forms, including symphonic poems, orchestral suites, or concert overtures, where the composer might provide a written narrative or title that guides the listener's imagination. This allows the audience to form mental pictures or emotional responses based on the music, enhancing the listening experience by connecting it to an external concept or idea.

In contrast, purely instrumental music without themes does not aim to tell a specific story or evoke imagery, compositional forms that follow strict guidelines do not necessarily focus on narrative, and improvisational music may prioritize spontaneity and individual creativity over conveying a structured story or imagery. Thus, the essence of program music lies in its ability to communicate a particular message or narrative through sound alone.