How did Vulgar Latin contribute to the development of Romance languages?

Vulgar Latin, the nonclassical, spoken form of Latin used by the general population of the Roman Empire, served as the direct ancestor of the Romance languages. Its evolution into these modern languages involved several key shifts:123

• Grammar: Vulgar Latin moved away from the complex, synthetic structure of Classical Latin, favoring more "analytic" constructions. For example, the use of prepositions replaced many traditional case endings, and word order became less flexible to clarify relationships between words.42
• Vocabulary: Speakers increasingly rejected sober classical terms in favor of more colorful, popular alternatives, such as diminutives and derivatives (e.g., preferring portare over ferre).2
• Phonology: Significant changes occurred, including the loss of the system of long and short vowels, which fundamentally altered the language's rhythm. There was also a general tendency toward the shortening of unaccented syllables and the loss of word-final consonants like m.2

These shifts, documented in texts like the Appendix Probi, reflect the transition from the standardized classical language to the diverse vernaculars that eventually emerged as distinct Romance languages.25