We've all seen the meme "what year is it?" "2000 BC" "BC?" "Before Christ." "Before who?"
But it got me thinking, how did people way back then keep track of the year? Did they even care to? Was it different per civilization?
The Christian BC/AD calendar is just one amongst many possible systems of year counting. Various other alternative calendars exist, as we can see from the appropriate section of the FAQ, Other Dating Systems under Calendars, if your browser doesn't automatically take you there. And the BC/AD calendar is hardly universal today; Japan still officially makes use of regnal years, counting how long the current Emperor has reigned. 2020 is Reiwa 2, the second year of the Reiwa era. 2000 was Heisei 12, while 1980 was Showa 55.
Bonus: BC/AD is hardly the only Christian calendar, even; there's the Byzantine Anno Mundi as explained by u/WelfOnTheShelf.