Recently one of my friends told me that there is distinct difference between 'know of something' and 'know about something' expressions.

  • 'know of' is used when you have personal experience with what you are talking about
  • 'know about' is used when you have heard about the subject but never had any experience with it.

This contradicts with my experience. To me it seems like 'know about' is used in every situation and the use of 'know of' is mostly limited to 'not that I know of' expression. Short google search seems to support my point of view, there are articles named '10 things I know about journalism' where person is speaking from the experience and not that many encounters of 'know of' expression anywhere.

So, is my friend's statement true?

5 Answers 5


I would use the expression "I know Smith" if I have had personal experiences with the person.

For me, "know about" means that I have heard many things about this person, or have researched him (such as if I were to say "I know about Einstein, he invented general relativity"), while "know of" suggests that I have merely heard of this person in passing, or have a very limited knowledge of this person (such as if I were to say "I know of Madame Curie", the emphasis being on the word "of", and usually as a reply to someone asking "Have you heard of Madame Curie?").

Therefore, I would say your friend is wrong in his characterization of the former, and correct in his characterization of the latter.

  • 6
    +1 - spot on. "I know John" implies a personal relationship. "I know about John" implies learning info about John from a third party. "I know of John" means the name rings a bell.
    – KeithS
    Jun 14, 2011 at 22:15
  • That's an important distinction. Many English learners in my country keep confusing those expressions. No you don't know Robert Downey Jr., you just know of him! Nov 12, 2016 at 14:36
  • Would you say Let me know whether you know ()/(of)/(about) a house to rent?
    – skan
    Apr 28, 2017 at 10:08
  • @Rofler, "A reply to someone asking"? Nah. It's easy to see that your analysis is wrong because you have simply changed the question into heard vs heard about vs heard of.
    – Pacerier
    Jun 19, 2017 at 12:26

My immediate thought was the opposite of your friend:

I know of tensor calculus (I have heard the name, but that is about all I know.)

I know about tensor calculus (I have learned this subject and can do the calculations.)

I know all about tensor calculus (I am an expert)

  • Would you say Let me know whether you know ()/(of)/(about) a house to rent?
    – skan
    Apr 28, 2017 at 10:09
  • 1
    @scan: I'd use "of" if I just wanted an address, "about" if I wanted full and complete details. Apr 28, 2017 at 11:28

If I knew somone personally, I would state simply that "I know" them – not that I "know about" them. In my experience, people generally ask "do you know about....?" if they want to question your knowledge of a specific event or characteristic related a person; for instance: "do you know about what happened to Freddy yesterday?"

As for the term "know of", I tend to agree with you in that the term implies a limited knowledge of a subject. However, as an Australian, I know it is very common practice here to respond with "I know of them" when somebody asks you about someone you are familiar with, but have never met or communicated with.

For example, Q: "Do you know Fred Bloggs?" A: "I know of him..."

Another situation in which you might use the term "know of", is if you were acquainted with someone, but wanted to imply a distance between yourself and that person, or be coy about how well you know them. (Perhaps they have a bad or questionable reputation, or you simply don't like them).

Here's an example of a situation in which one might use the term "know of" to suggest indirect knowledge of a person (through a mutual acquaintance, or the like): "I know of a man who could pick that lock for you in three seconds flat."


I found this page, because I want to know the correct use of "know of" in this example:

  • I know more of aliens than I will ever learn from reading.
  • I know more about aliens than I will ever learn from reading.

In the first example, I think it is indeed true that the person has first-hand experience. For instance, because (whether or not this is a fictitious situation) this person was abducted by aliens, or had ancient memories from when he was still an alien, etc.

In the second example, he knows a lot about aliens, maybe through movies, but not first hand and not from books. However, if the person is a scientist, studying aliens, and went to different planets to study them, he can perfectly say this.

In this example, I tend to agree with your friend, but I hoped to find a better reference to decide between the two.

  • Would you say Let me know whether you know ()/(of)/(about) a house to rent?
    – skan
    Apr 28, 2017 at 10:09

Well, it's a bit complicated. The first sentence sounds incorrect. "Of" implies little is known. However, the second one doesn't work either; it needs some revising (present tense in the first part does not agree with future tense in the second). Consider: I know more... than you ever will; I can learn more about aliens from meeting/living with them than .... . Also, depending what aliens you are talking about, it might be impossible to Experience them.


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