A Tone Poem is an orchestral or solo work, in which the composer attempts to paint an impression of some scene or mood. Other terms for the same thing include Descriptive Music, Programme Music, or sometimes Symphonic Poem. The opposite term is Abstract Music, or Absolute Music.
The rhythm may be slow and the dynamics quiet, but the music tuneful in a major key, to give the impression of happy serenity experienced in the countryside. It may be fast, loud and furious, to suggest battles or storms. It may be quiet, slow but in a minor key to indicate sadness or grief. It may be at a moderate tempo, fairly loud, but stately, with themes played on the trumpet, to suggest a military triumph. The resources of the full symphony orchestra give the composer a powerful set of paint-brushes with which to paint his tone-picture.
A Baroque work which is effectively a Tone Poem, is the Four Seasons, by Vivaldi. A work from the classical period is Beethoven's Pastoral Symphony no 6 in F, although most people would agree that Beethoven became the first Romantic composer when he wrote this symphony. The composers labelled Impressionists, such as Debussy and Delius, were especially famous for writing Tone Poems.
Examples of Tone Poems include Rimsky-Korsakov's Scheherezade, Debussy's Afternoon of a Faun, Dukas's Sorceroer's Apprentice, and Richard Strauss's Till Eulenspiegel.