Is it its or it's?

One of the weirdest situations when using an apostrophe is the decision between its and it's. The first is a possessive and the second is a simple contraction -- a combination of the words it and is. If we want to combine the words do and not into a contraction, we write the word don't. Easy enough. So when we want to combine it and is into a contraction, we write it's: It+apostrophe+s. The weird situation is that sometimes we want to write a possessive using the same letters: its. And we know that possessives use an apostrophe: Bob's. So we assume the same case here! But no, the truth is just the opposite. If I write "Bob's car quit when its engine died," I will put the possessive apostrophe in Bob's car but I don't put the possessive apostrophe in its engine. If I wrote it's engine, that would mean it is engine which would make the sentence sound really silly. So, the thing to remember is that when it comes to possessives, its leaves off its apostrophe.

Does this need an apostrophe?

Most of the time, when people ask this question, they are talking about possession and ownership. We know how to use apostrophes for words like don't, didn't, and can't (showing contraction). Showing possession with an apostrophe is more difficult for a lot of us. We are just not sure what needs an apostrophe. Bob's car might make sense, because Bob owns his car. But Bob also owns his knee, as in Bob's knee hurts. Even more strange, Bob owns his plans: Bob's dinner plans were ruined. He also owns his height: Bob's height is 5'8". A house can own its gutters: The house's old gutters fell off. Even an idea can own its own time: An idea's time has come. The key to deciding if the word takes an apostrophe is ... does it own the words that follow it? If a sentence reads "Kids on the playground like to test the swings height," the possessive in the sentence is not kids. The word kids is followed by "on" and the kids don't own the word "on." However, the word swings is followed by the word height, and the swings own their own height, so swings takes an apostrophe. The only problem left is to decide where to put the apostrophe! Is swing's or swings' correct? Check for the solution in my post about the thumb trick for apostrophes.

Where does the apostrophe go?

So let's say Bob owns a car, and you want to write that it is Bob's car. Bob takes an apostrophe and an "s" to show possession of the car. But Bob is a pretty simple example. What if you are writing about the mailbox that belongs to Mr. and Mrs. Jones next door? Or what if you are referring to the goat farm that Silas owns? Well, try my thumb trick to figure out where the apostrophe goes. Write the two choices down: Jone's mailbox and Jones' mailbox. Then in each choice, stick your right thumb over the apostrophe and everything to the right of it. The first choice will leave you with Jone. Hmm...that looks funny; definitely not their last name. The second choice turns out as Jones, and that is their name, so you have found your answer. Try this again with Sila's goat farm and Silas' goat farm: you discover the same secret, that the name won't make sense when you cover up the apostrophe on the incorrect choice. My thumb trick has never failed me. It even handles confusing situations like this: Toys covered the girls' floor all the way to their bunk beds. Is girls' floor or girl's floor correct? You can tell there are two or more girls because "they" have "bunk beds" so if you use the thumb trick, you want to see the word girls before the apostrophe. Who knew your thumb could be so smart!