English is a modern language, while Sanskrit, Latin, and Greek are all classical languages.

Sanskrit is the oldest known classical language, with its earliest texts dating back to around 1500 BCE.

Latin was the lingua franca of the Roman Empire, and it continued to be used as a language of scholarship and diplomacy in Europe for centuries after the fall of the empire.

Greek was the lingua franca of the Byzantine Empire, and it continued to be used as a language of scholarship and diplomacy in the Eastern Mediterranean for centuries after the fall of the empire.

Arabic was the lingua franca of the Islamic world, and it continues to be used as a language of scholarship and diplomacy in many Muslim countries today.

Sanskrit was the lingua franca of the Indian subcontinent for centuries, and it continues to be used as a language of scholarship and religious ritual in many parts of India today.

Sanskrit was the lingua franca of Southeast Asia for centuries, and it continues to be used as a language of scholarship and religious ritual in many parts of Southeast Asia today.

Chinese was the lingua franca of East Asia for centuries, and it continues to be used as a language of scholarship and diplomacy in many East Asian countries today.

Persian was the lingua franca of Central Asia for centuries, and it continues to be used as a language of scholarship and diplomacy in many Central Asian countries today.

Nahuatl was the lingua franca of the Americas for centuries, and it continues to be used as a language of scholarship and religious ritual in many parts of Mexico and Central America today.

Arabic was the lingua franca of Africa for centuries, and it continues to be used as a language of scholarship and diplomacy in many African countries today.

Hawaiian was the lingua franca of Oceania for centuries, and it continues to be used as a language of scholarship and religious ritual in many parts of Oceania today.

All of the classical languages listed above are still spoken today, although some of them are only spoken by a small number of people.

Latin has had the greatest impact on the world, as it was the lingua franca of the Roman Empire and the Catholic Church for centuries. It is also the root of many modern European languages.

Latin is the most widely studied classical language today, as it is a required language for many students in high school and college.