Which time period is known for its colorful harmonies with altered and unusual chords?

The Romantic period is indeed recognized for its colorful harmonies and the use of altered and unusual chords. During this era, which spans approximately from the early 19th century to the early 20th century, composers aimed to express deep emotions and individualism, leading them to explore more complex harmonic structures.

This creativity resulted in the use of chromaticism, modulations to distant keys, and an expanded harmonic vocabulary that included augmented and diminished chords alongside traditional triads. Composers such as Franz Schubert, Robert Schumann, and Richard Wagner employed these techniques to evoke specific moods and feelings, further enriching the emotional and tonal palette of music from this period.

In contrast, the other periods reflect different characteristics: the Classical period focused on clarity, balance, and form, primarily utilizing diatonic harmony; the Baroque period was known for its counterpoint and figured bass, with less emphasis on colorful chord progression; and the 20/21 centuries feature an even broader spectrum of harmonic experimentation and avant-garde techniques, but this period is more diverse and still evolving.