“Anno Domini” is a Latin phrase that means “In the Year of Our Lord” in English. It’s often abbreviated as “AD.” This term is used to identify or number years in the Christian era, counting from the traditional year of the birth of Jesus Christ. The widely-used Gregorian calendar is based on the concept of Anno Domini.
For example, if a historical event is said to have happened in the year 500 AD, it means 500 years after the birth of Jesus Christ. The years before the birth of Christ are typically denoted as “Before Christ” (BC). It’s important to note that the year 1 AD immediately follows the year 1 BC; there is no year 0 in this system.