Adding to Stani's answer: 1) Academics, historians, and textbooks now often use the terms CE and BCE ("common era" and "before common era") instead of AD and BC. This maintains a more neutral point of view with regard to religion, and it avoids the obvious problem of Jesus Christ having been born in the year 4 BC (i.e. "before Christ.") If you are writing in an academic context, consider using BC and BCE. I will use AD and BC for the rest of this posting, because they are more common in everyday life. 2) There isn't any year 0 AD. There should be, but there isn't. This drives software engineers like me absolutely crazy. It's wrong. It's a bug! But it is what it is. The first year AD was 1 AD. The year before 1 AD was 1 BC. This is why people obsess over what years constitute "the twentieth century." The first century began on January 1, 1 AD and ended on December 31st of the year 100 AD. That is, it consists of years 1 through 100, not 0 through 99. The result is that the nineteenth century was 1801 through 1900, inclusive, and the twentieth century was 1901 through 2000, inclusive. Of course, everybody always celebrates "the turn of the century" a year too early, when the 9's change to 0's. Everyone breaks out the champagne and ignores the party pooper in the corner who says "but the new millennium doesn't begin until 2001." 3) When there are less than four digits, it doesn't sound like a year. Therefore, it is common to include the words "the year," as in "the year three-twenty-five."

3200 BC THIRTY TWO HUNDRED BC / THREE THOUSAND TWO HUNDRED BC both are correct 0 AD ZERO AD or YEAR ZERO I heard both though it doesn't really exist cause 1 AD comes after 1 BC 100 AD ONE HUNDRED 110 AD ONE HUNDRED TEN / ONE HUNDRED AND TEN / one ten AD I suppose is possible but sounds very casual 125 AD ONE HUNDRED TWENTY FIVE / ONE HUNDRED AND TWENTY FIVE / again one twenty five sounds too casual but possible I guess 1000 AD ONE THOUSAND / ten hundred is definitely wrong 1600 AD SIXTEEN HUNDRED or ONE THOUSAND SIX HUNDRED both are correct 1010 ONE THOUSAND TEN / ONE THOUSAND AND TEN / ten ten sounds wrong to me You can also say CE and BCE instead of AD/BC. Also I think it depends on the variety of English. For example in North American English people will tend to say THIRTY TWO HUNDRED instead of THREE THOUSAND ONE HUNDRED. Also "and" can be used or not used depending on where the speaker is from. Somebody correct me if I'm wrong though.