[Wings of Fire]

Year 1 (I) was a common year starting on Saturday or Sunday (link will display the full calendar) of the Julian calendar (the sources differ, see leap year error for further information) and a common year starting on Saturday of the Proleptic Julian calendar. At the time, it was known as the Year of the Consulship of Caesar and Paullus (or, less frequently, year 754 Ab urbe condita). The denomination 1 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. It was the first year of the Christian/Common era. The preceding year is 1 BC in the widely used Julian calendar, which does not have a "year zero".

This calendar era is based on the traditionally reckoned year of the conception or birth of Jesus of Nazareth, with AD counting years after the start of this epoch, and BC denoting years before the start of the epoch. Alternatively, the abbreviations CE and BCE are used, respectively.

There is no year zero in this scheme, so the year AD 1 immediately follows the year 1 BC. This dating system was devised in 525, but was not widely used until after the Carolingian Renaissance.

Wikipedia people.

It's not hard.