First of all, I don't know how to correctly call this. Possessive case? Educate me, please. Lol.

I've been confused a long time when using 's and of in different cases when I try to point out the belonging or possession of something. I'm writing or talking and I pause when I have to say that something belongs to someone, and it's pretty annoying stumble always with the same stone. Could you help me to clarify my ideas?

Yes, I've looked at some books and sites, but I'm still doubtful.

Here I'm adding some examples. They're not too numerous though. Some of them are pretty simple, but yet they're pretty confusing for me since I really don't know what's the best way to express my idea.

The house of Mary. Mary's house

I know these sentences are both correct. What I'm wondering is what should I consider to choose one option above the other one.

Now something more complicated:

Iron Age
Age of Iron
Iron's Age

By the way, my native language is Spanish.

  • Please edit in some examples of sample phrases you have doubts about
    – user22427
    Feb 22, 2018 at 14:59
  • What is your specific question? It's impossible to write an entire book here. Please ask specific questions. This question is like saying: How do you use the subjunctive in Spanish....see what I mean? Yes, it's called "the possessive case". Why don't you try some exercises and then tell us what you don't get? grammarly.com/blog/possessive-case
    – Lambie
    Feb 22, 2018 at 16:55
  • Ok, @JanDoggen, I will look for some examples and I will add them.
    – carloswm85
    Feb 22, 2018 at 17:02
  • @Lambie, precisely what I need is guidance. I can't write a specific question and this subject since I'm not sure what I'm talking about (yet). I'm sorry for my noobness (lol).
    – carloswm85
    Feb 22, 2018 at 17:03
  • Yes, and I have given you that plus I responded to the specific issues raised by your questions with specific reference to Spanish.
    – Lambie
    Feb 22, 2018 at 18:59

4 Answers 4


Okay, there are three forms:

A's B (ex. the car's engine)

B A (ex. a car engine)

B of A (ex. the engine of the car)

The first form indicates "possession". B belongs to A.

Perhaps I need to clarify that the word "possession" here is used very loosely. It could refer to almost any sort of relationship. If I say, "Fred's pencil", I mean the pencil that Fred owns, that belong to him and that he can do pretty much anything he wants with. If I say, "Fred's city", I probably do not mean that Fred owns the city and can do whatever he wants with it. I probably mean something more like, the city where he lives.

The "B A" form indicates a "type". When I say, "a car part", I mean a part that is of type "car". In this case, a part that comes from a car or that is normally used in a car. The difference between this and "B's A" can be subtle, but in general, the "B's A" indicates association with a particular thing, while "B A" indicates an association with that type of thing in general. Like if I say, "This is my car's battery", I mean that it is the battery for this particular car. But, "This is a car battery" means it is a battery intended to be used in a car, but which I am not (presently) associating with any particular car.

So, "the Iron Age" means an age that is associated with iron. Not a particular piece of iron, just iron in general.

"A of B" can be used in place of either of the previous two forms. Sometimes we distinguish by the use of articles, pronouns, or other adjectives. Like, "this is the battery of my car" is the same as "this is my car's battery". Other times we just tell by general context. "This was the Age of Iron" is the same as "this was the Iron Age", but "This was the Era of Napoleon" is the same as "this was Napoleon's Era".

Whether you use the "of" form or one of the other two forms just depends on what makes the sentence flow smoothly. Sometimes a sentence is more clear with one form than the other, or just has a nicer rhythm.

  • In your forms, you don't show that: the engine of the car = the car's engine. You post it as if it was unrelated. There's a difference between ownership and a noun being paired with another noun where it belongs with it but there is no ownership.
    – Lambie
    Feb 22, 2018 at 19:05
  • 1
    I thought I covered that in the penultimate paragraph: "this is the battery of my car" is the same as "this is my car's battery". Sorry if it wasn't clear. Not sure what you mean by the part about ownership.
    – Jay
    Feb 22, 2018 at 22:23
  • John's book versus my car's battery. With people and things is where the complications set in. No worries. I dislike this type of question because I specifically answered the part about Spanish and didn't even get acknowledgement for that. So...."pearls before you-know-what".
    – Lambie
    Feb 22, 2018 at 23:43
  • I always had been studied that 's form cannot be used for inanimate objects
    – IC_
    May 30, 2020 at 8:17
  • @Herrgott Hmm, I'm not aware of any such rule. It's very common to use the apostrophe-s form where either the owner or the subject (or both) is inanimate. "The car's driver", "Bob's car", "the car's engine", etc.
    – Jay
    May 31, 2020 at 5:32

Both A's B and the B of A are grammatical and idiomatic and convey the same meaning. In speech and informal writing, A's B is far more frequent. In formal writing, the B of A is less rare because formal writing often involves relatively complex sentences.

For example, Last year, the X corporation bought the French assets of Y corporation, which was then still tied up in bankruptcy.

  • Yes, but there are many complicated examples....sometimes to avoid awkwardness we use of and other times we don't. I often edit translations where even easy 's are avoided, creating very heavy text. The company's assets and the company assets are both right, for instance, but used in different ways.
    – Lambie
    Feb 22, 2018 at 16:58
  • 1
    @Lambie I basically agree. I was trying to give a simple answer to what was a basic question. Both usages are fine. One is much more common in speech and informal prose. In formal prose, the choice depends on both sentence structure and style. I did not really try to explore those subtleties. Feb 22, 2018 at 23:36
  • Yeah, I know. It gets incredibly complicated. That's why I said a beginner's guide.....
    – Lambie
    Feb 22, 2018 at 23:41

A simple guideline for beginners about the possessive case and ownership of things or a thing belonging to a person:

John has a car. = John's car is red. Not Jim's.

Please note: In speech, there is no need to REPEAT the object.

John has apples and oranges. John's apples are on the table. Jim's aren't. They're in the garage.

Possessive case and objects or things (this is the area where learners run into trouble):

The door handle is broken.

We tend not to say: the handle of the door. That would only be if there is some doubt about it or ambiguity in a particular context. "The handle of the front door is what I'm talking about, not the back door".

> When a word is closely associated with the thing, we tend to use two nouns: door handle, car door. This happens a lot. For example: the results of the lab tests becomes: the lab test results. An adjectival use is created from the noun: lab tests.

However, it can get tricky: What are the parts of an engine or car? What are car or engine parts?

Sometimes, the meaning will change. Car parts or engine parts are things that can be replaced. BUT parts of a car can also be understood as: the engine, the hood, the roof, the chassis, and not something replaceable as in something you can buy at an auto parts' store. The parts of a car are not necessarily car parts! This can only be learned through experience. There are no hard-and-fast rules for it. In fact, auto parts' store is also written auto parts store without an apostrophe but you need the s.

(The only good news about the word parts and part, is that it is one of the few causing major issuers for ELLers.)

The hospital's x-ray machines are very new. Here, the normal possessive case is used. That is because x-ray machines are not "part" (there's that word again) of a hospital in the same way that a handle is part of, or associated with, a door.

The ship's engines have been replaced.

**The opinions of editorial writers"= Editorial writers' opinions.

In the plural, there is no s added after the apostrophe, generally speaking (there can be but it is too advanced for a beginner's guide).

Iron Age=a proper noun, is already accepted. It never was the Age of Iron as a term. Of course, you could use The Age of Iron in a title, if you chose to, but Iron Age is in the canon. Therefore, there is no doubt about it. Just like: The Gilded Age. These are historical proper noun terms. **In deciding on terms like this coming from Spanish, you have to check the term. La Edad de Oro would be: The Golden Age, these are specific terms used in historiography/mythology, etc.

In English, they never had OF in them. La edad de oro del capitalismo, for example, becomes the golden age of capitalism. These kinds of term require being checked for usage by non-English speakers.

Literary terms and titles are another matter, slightly, and call for separate consideration.

  • After reading all the answers and comments, I think that I should start every time with the sentence in the form "A of B" and see how it sounds/feels under the for "B's A" or "A B". And make a choice between the three options if possible and/or necessary. Doing this just as a rule of thumb.
    – carloswm85
    Feb 23, 2018 at 12:53
  • Lambie, what's OF? You should edit "La edad de ora del capitalismo" for "La Edad de Oro del Capitalismo".There's a difference there.
    – carloswm85
    Feb 23, 2018 at 12:55
  • @CarlosW.Mercado OF is the prounoun: of. I see perhaps I was not clear about Iron Age and Golden Age. One thing is possessive case in English; another is translation of x de y from Spanish. What I am trying to communicate to you is that the fact of having a DE in Spanish in a proper name does not mean a possessive case in English. El coche de mi hermana: my sister's car. Right. But: La edad de oro, the golden age. golden age is not possessive in English; it's adjectival or an adjunct (more modern terminology).
    – Lambie
    Feb 23, 2018 at 16:33
  • In English, golden age and Iron Age never had the word "of" in them. That is only an issue in translation where one can mistakenly believe that edad de oro might be age of gold, and it is not. It is not an issue in English itself. Is that clearer?
    – Lambie
    Feb 23, 2018 at 16:35
  • Yup, clear enough.
    – carloswm85
    Feb 23, 2018 at 16:52

There is not so much a rule as a best practice that "of something" should not be used too many times in a row. E. g., if you have to say, "W of X of Y of Z", consider replacing at least one of those (or a couple) with the "'s" form. Generally, already two "ofs" in a row is something to be avoided.

When the "possessor" is inanimate, "'s" is usually out of place. It can be "the roof of the house" but not "the house's roof". In case we have many "ofs" in a row and need to do something with this roof, we turn "house" into a noun adjunct (adjectify it, so to speak) without using "'s" ("the house roof").

When the possessor is a person, it should generally be "'s". E.g., "Sarah's doll", not "doll of Sarah". But syntax considerations might sometimes necessitate breaking the "'s" construction. This will happen in those cases where you need to mention the object/entity in question first, because the sentence is better formed that way.


We don’t know, beyond the statements of Trump Jr. and others, what happened in the meeting... (source)

In this case, "beyond Trump Jr.'s and others' statements" is a bit awkward and puts the important word (statements) too far into the sentence, so the reader has no clue about what he's reading about until he comes to the word "statements".

The iconic car had also featured in the novel Dr. No, where it was the personal car of John Strangways... (source)

Here, the sentence centers on cars, so once we begin the subordinate clause, it is "the car" that is mentioned first, and then its possessor is named.

  • I query your guidance re the use of the possessive apostrophe with inanimate objects. There's nothing wrong with the house's roof, the car's fender, the umbrella's cover, the coat's lining etc. That's not to question the frequent use of noun adjuncts in these cases. Feb 22, 2018 at 16:30
  • @RonaldSole I refer you to comments under this question. There might be nothing theoretically wrong with that, but there might be something practically wrong, in that a certain construction simply isn't used a certain way all too often. In the same way as there is nothing theoretically wrong with piling on of "of X of Y of Z"—and yet it is usually avoided.
    – user68912
    Feb 22, 2018 at 16:35
  • @RonaldSole See, "X of Y" and "Y's X" are basically equivalent, but there will be a certain preference for one over the other in certain situations. And this choice of one variant over another will be characteristic for a language.
    – user68912
    Feb 22, 2018 at 16:37
  • W of X of Y of Z??
    – Lambie
    Feb 22, 2018 at 16:55
  • @Lambie What exactly is your question about?
    – user68912
    Feb 22, 2018 at 17:09

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