BC AND AD
If somebody asks you the date, you will probably mention the day, month, and year, 2000 and something. These years are counted from the date generally assigned to the birth of Jesus Christ, the founder of Christianity. So, 2000 means 2000 years after the birth of Christ. All dates before the birth of Christ are counted backward and usually have the letters BC (Before Christ) added on. In this book, we will refer to dates going back from the present, using 2000 as our starting point.
Letters with dates
BC, we have seen stands for ‘Before Christ.’
You will sometimes find AD before dates. This stands for two Latin words, ‘Anno Domini’, meaning ‘in the year of the Lord’ (i.e. Christ). So 2012 can also be written as AD 2012.
Sometimes CE is used instead of AD and BCE instead of BC. The letters CE stand for ‘Common Era’ and BCE for ‘Before Common Era’. We use these terms because the Christian Era is now used in most countries of the world. In India, we began using this form of dating from about two hundred years ago.
And sometimes, the letters BP meaning ‘Before Present’ is used.
Some important dates
* The beginning of agriculture (8000 years ago)
* The first cities on the Indus (4700 years ago)
* Cities in the Ganga valley, a big kingdom in Magadha (2500 years ago)
* The present (about 2000 AD/CE)
Source: This topic is taken from the NCERT TEXTBOOK