What's it mean when "s" is added at the end of year like this?

Native speaker’s answer
Rebecca
Good question. When "s" is added to the end of a year, it means that the year is non-specific and is referring to a decade of time (from year 0 to 9 of a decade). So, the "1800s" being mentioned here is just referencing the general period of the 19th century, and not any specific year. It usually refers to a decade of time. You might also sometimes see the first two digits being omitted from a year and an apostrophe placed in front (like '90s). The apostrophe indicates that the first two digits have been omitted. Based on common sense, we can assume that the omitted numbers are either 19 or 20. Ex: I enjoy listening to music from the '90s. ('90s = period from 1990-1999) Ex: I was born in the 1980s. (1980s = period from 1980-1989)