Question

What is the rule for the correct use of apostrophes when writing about years? For example, is it the 1970s or the 1970’s?

Answer 1

Hint: In languages that use the Latin alphabet and some other alphabets, the apostrophe (' or ') is a punctuation mark and often a diacritical mark.
It serves three purposes in English:
- The absence of one or more letters is indicated (as in the contraction of "do not" to "don't").
- The eagle's wings, "in one month's time," and "at your parents' [home]" are examples of possessive case marking.
- Individual character plurals (e.g. "p's and q's") are marked.

Complete answer:
An apostrophe is a small punctuation mark ( ' ) placed after a noun to show that the noun owns something. When omitting numbers, an apostrophe should be used in the same way it is when making contractions. If you're referring to the 1950s, you can omit the first two digits and just call it the '50s.

Consider the following sentences:
In the '70s, the word "Far out!" was coined. It was used while people were discussing something that they felt was interesting.

During the '90s, we used to love exchanging pogs with our classmates at school.
If you want to type out the whole year, keep in mind that an apostrophe should not be used between the year and the letter s. Unless the year is possessing something, this isn't grammatically right.
- 1970's were incorrect.
- 1970s is right.

Note: Remember that there is no apostrophe when you have the complete date. When it's just the last two digits, though, you'd use an apostrophe. Consider it as a contraction. With "is not," there is no apostrophe, so when you take something off, you put an apostrophe—"isn't."