Just as the word "Classic" brings to mind certain concepts, the word "romantic" is even more evocative. Such examples as Victor Hugo's "Les Miserables" and the paintings of Delacroix - Romaticism implies fantasy, spontaneity and sensitivity.
The Classical period was oriented towards structural clarity and emotional restraint. Classical music was expressive, but not so passionate that it became unbalanced. Beethoven, who was actually responsible for "lighting the flame of Romanticism" and is considered a bridge between the eras, always fought (not always successfully) for maintaining the equilibrium of a piece. Most composers of the Romantic period followed this model of Beethoven's and looked for their own balance between emotional intensity and classical form. "Musical story-telling" also started to play a not negligible role, with pieces having to express some factual content, not only in opera but in purely instrumental compositions. The genre of the symphonic poem was brought to the fore during the Romantic era. In its performance, a conposition had to set a scene, and then tell a story from that scene.

The color of sound is a characteristic, expressive device of Romantic music. New instruments, never before featured there, found their way into orchestras and composers experimented with new ways of wresting new sounds out of old instruments. A large pallet of the colors of sound, necessary for expressing exotic scenes, was an element no composer's technique could be without. Exoticness was an obsession of the 19th century. Russian composers wrote music describing the Spanish countryside (ie. Capriccio Espagnol by Nikolai Rimsky-Korsakoff) and German composers about Scotland (ie. Mendelssohn's Scottish Symphony). The stories in opera were also mostly set in exotic localities, such as Verdi's "Aida" in Ancient Egypt.
Another new element brought to music by the Romantic period was the appropriation of folk music for Classical music. Nationalism became a driving force in the later Romantic period, with composers trying to express their cultural identity through their music. These trends were mostly apparent in Russia and the countries of Eastern Europe, where elements of folk songs even became parts of symphonies, symphonic poems and other forms.
The Romantic era was a paradise of virtuosos. Exceptional talents of interpretation were extremely popular. Franz Liszt, a Hungarian pianist and composer, played the piano with such vigour and passion that women fainted. Because so many of the authors of this period were such virtuosos, the music that they wrote is also very demanding in its technical execution.