1BC

1BC refers to the year 1 before the Common Era, also known as 1 BC. This year is part of the Anno Domini (AD) or Common Era (CE) dating system, which is widely used in the Gregorian calendar. The system divides time into BC (Before Christ) or BCE (Before Common Era) and AD (Anno Domini) or CE (Common Era), with the transition occurring between 1 BC and 1 AD. There is no year zero in this system.

The transition from 1 BC to 1 AD marks a significant point in historical and chronological calculations. Understanding this numbering system is crucial for accurately interpreting historical timelines and events. The lack of a year zero means that the year immediately following 1 BC is 1 AD, and the year immediately preceding 1 AD is 1 BC. This convention is consistent across most historical and academic disciplines that utilize the Gregorian calendar.

The concept of BC/AD or BCE/CE was developed by Dionysius Exiguus in the 6th century AD. He intended to calculate the date of Christ's birth, but his calculations are now understood to be slightly inaccurate, with Christ's birth likely occurring a few years earlier than 1 AD. Despite this historical inaccuracy in the original calculation, the dating system itself, including the designation of 1 BC as the year preceding 1 AD, remains the standard for chronological purposes.