It’s: This contracted word is one of the most mis-used in the English language. (Actually, I’m not sure of that, but it’s the one that I notice the most; and it’s the error that bugs me the most.)
There is no reason for its ubiquity. The rule is so simple. Yes, it’s simple. And perhaps after I give you my explanation, you will agree.
So here goes:
One of the roles of an apostrophe is to replace one or more missing letters in a contraction. We might want to contract or reduce “it is” to the contraction “it’s” to make written or spoken speech more casual or informal. In the word “it’s” the second “i” has been removed and replaced by an apostrophe.
In other words, what was “it is“ becomes ”it is“ minus the letter “i.“ “It is” then scrunched together using an apostrophe to create one word: “it’s.”
It’s the only correct use of “it’s.“
In short, “it’s” always, always, always means “it is” or “it has.” Yes always.
You see? It’s a simple rule. Yes it is.
The non-contracted word “its” is the one that most people mean when they incorrectly use ”it’s.” The non-contracted word “its” means “what belongs to” something. It indicates possession.
One easy way to remember this is to remember, “The cat chased its tail.”
If you write, “The cat chased it’s tail,” you are saying, “The cat chased it is tail.” And that’s just nonsense. Yes, it is.
People make this mistake because they are used to showing possession with an apostrophe. We all say and write, “Jennifer‘s cat.” or “The cat‘s tail.” Just remember not to write, “The cat chased “it’s“ tail.”
As you now know, that’s just nonsense.