"Before Christ" (BC) refers to the years in the Gregorian calendar that occurred before the estimated birth year of Jesus Christ. This system of dating is used to denote years in history, with BC years counting backward from 1 BC, which is immediately followed by AD 1 (Anno Domini). The BC era includes significant events and civilizations, such as the rise and fall of the Roman Empire, the construction of the Great Pyramids of Giza, and the development of early writing systems like cuneiform in Mesopotamia. This period laid the foundation for many aspects of modern culture and society.