Final answer:
The most important genre of secular music in the Renaissance was the Italian madrigal, known for its polyphonic style and expressive text settings. It greatly influenced the development of secular music, which encompassed a variety of other forms but was predominantly characterized by the madrigal.
Step-by-step explanation:
The most important genre of secular music in the Renaissance was the Italian madrigal. This form of music was significant as it was independent of the church and represented a major development in the composition of secular songs. The madrigal was characterized by its elaborate and expressive nature, and typically composed for several voices, becoming a sophisticated form of music with a rich texture and harmonic complexity. The popularity of the madrigal led to the development of related forms, such as canons, which further enriched the variety of secular music available during this time.
Secular music of the Renaissance era included a wide array of genres, but not all have survived in the historical record due to the perishable nature of music distribution before the widespread availability of printed music. Nevertheless, other secular vocal genres such as the German Lied, French chanson, and the Spanish villancico also enjoyed popularity alongside mixed forms like the motet-chanson.
Despite the flourishing of secular music, sacred music forms such as masses and motets remained central throughout the Renaissance period. Composers would often adapt secular forms like the madrigal for sacred music compositions, showing a crossover between the two musical spheres.