Year 1 BC was a common year starting on Friday or Saturday in the Julian calendar (the sources differ; see leap year error for further information) and a leap year starting on Thursday in the proleptic Julian calendar.

For example, AD 1 means the year Christ was born. 1 BC, on the other hand, is the year before that. The AD/BC dating system is used in the Gregorian Calendar. The Gregorian calendar was started by Pope Gregory XIII in the year 1577. It uses the labels AD and BC to mark the years.

The 1st century BC, also known as the last century BC and the last century BCE, started on the first day of 100 BC and ended on the last day of 1 BC. The AD/BC notation does not use a year zero; however, astronomical year numbering does use a zero, as well as a minus sign, so "2 BC" is equal to "year –1". 1st century AD (Anno Domini) follows.

In the modern calendar, we label all years with B.C. (before Christ) or A.D. (anno domini, or "in the year of our lord"). There is no "zero" year -- in this system, the year Christ was born is 1 A.D., and the year preceding it is 1 B.C.

This era, called Anno Mundi, "year of the world" (abbreviated AM), by modern scholars, began its first year on 25 March 5492 BC. Later Byzantine chroniclers used Anno Mundi years from 1 September 5509 BC, the Byzantine Era. No single Anno Mundi epoch was dominant throughout the Christian world.

CE is an abbreviation for Common Era. It means the same as AD (Anno Domini) and represents the time from year 1 and onward. BCE is short for Before Common Era. It can be used instead of BC (Before Christ) and stands for the time before year 1. CE and BCE are used in exactly the same way as the traditional abbreviations AD and BC.

Year 1 BC/BCE was a leap year starting on Thursday in the proleptic Julian calendar. Some sources list it as a common year starting on either Friday or Saturday. At the time, it was known as the Year of the Consulship of Lentulus and Piso.

AD or A.D. stands for Anno Domini and is a label for numbering years after Christ was born. BC or B.C. means Before Christ. The year Christ was born is considered AD 1 and the year before that is labeled 1 BC.

The year before AD1 was 1BC, or one year “before Christ.” When referring to dates before the birth of Christ, the higher the number the earlier the year. Since we mark years from a set point known as 1 — there is no year 0 — 3500BC was 5513 years ago.

2021年9月26日 · This calendar era is based on the traditionally reckoned year of the conception or birth of Jesus, with AD counting years from the start of this epoch and BC denoting years before the start of the era. There is no year zero in this scheme; thus the year AD 1 immediately follows the year 1 BC.