I know I’ve done a post about apostrophes before, but I thought I would focus on the most troublesome cases once again.
Most of the time, apostrophes show that one or more letters have been left out. This should help you to decide on the spelling, if you keep in mind which letters are missing.
You are = you’re (the “a” is missing)
Your just signifies that something belongs to you.
Here’s (here is) and example with both.
You’re going to miss your train.
Another way to think of which word (your or you’re) shows ownership is to think of the spelling. Your contains our, another ownership word. If it’s not our car, it might be your car.
there, their, and they’re
They are = they’re (the “a” is missing)
There, as in over there, should be easy to remember because it has here in it. If it’s not here, it’s there.
Their (which shows that something belongs to them) gives a lot of people trouble with spelling. Is it i before e? Not if it sounds like “a” as in hay and weigh. Easier yet, is to think of the word as the with ir tacked on. You’ll never spell it thier again.
Then there is who’s and whose.
Who is = who’s (the “i” is replaced).
Who’s going with me?
But to show ownership, it’s whose.
Who’s coming with me to confront the man whose son is a bully?
Let us go to the movie together. Yes, let’s. (the “u” is missing).
I’ll go if my mom lets (allows) us. No letter missing. No apostrophe needed.
Also if it means to rent out a place. She lets (rents out) the apartment upstairs. No apostrophe needed.
If you are just trying to write the plural form of a word, no apostrophe is needed.
A lot is an amount, a group, or a bunch. If you have many groups or bunches, you have more than one lot. You have lots. No apostrophe needed. And by the way it is “a lot” with a space between the two words. Not “alot.”
All the years in the decade from 1970 to 1980 are the years in the 1970s. It is a plural number (more than one year). There is no ownership and no letters are missing, so no apostrophe needed. So years in any decades are written without an apostrophe, e.g. the 1950s, the 1890s and so on.
Before you put an apostrophe in a word, ask yourself why you are doing it. Is it taking the place of a letter? Is it showing ownership? If not, then maybe it doesn’t need the apostrophe at all.