Marcus Ulpius Trajanus, commonly known as Trajan, was a Roman emperor who ruled from 98 to 117 AD. He is known for his military campaigns and expansion of the Roman Empire, particularly in the eastern territories. Trajan is also remembered for his public works projects, including the construction of roads, bridges, and aqueducts, as well as his philanthropy and social welfare programs. He is considered one of the "Five Good Emperors" of Rome and is often celebrated for his leadership and contributions to the empire.