was popularised by Bede, but is increasingly replaced with C.
However, in the modern age the actual meaning of A. is widely forgotten or misunderstood and the term simply signifies a different era from B. There is a common misuse as ' After Death'.
D.', which stands for Anno Domini (' The Year Of Our Lord') is increasingly seen as inappropriate given the majority who have different, if any, 'lords'.
But it is a separate issue requiring a separate ticket.
Edit: Ninja edits for clarity; changed some of my examples wrongly displaying "379 BCE" when I intended "380 BCE".
Many different calendars have been used since man began tracking time. The use of BC and AD for numbering calendar years was invented by Dionysius Exiguus in 525 AD.
Dionysius named the years relating to his cycle, BC meaning Before Christ, which starts with year 1 and AD meaning Anno Domini, the year of Our Lord referring to the year of Christ’s birth. For example, the first year began in 1 AD and ended the beginning of 2 AD.